This of course is what leads to the special called state convention in 1860 that defied Gov. Claiborne Jackson and voted overwhelmingly to remain in the Union. The fact of the matter is at that point in time the vast majority of the electorate (granted, property owning white men) slave owner or not was against seccesion.
I've alluded to extremes.
Frank Blair, Jr. and Lyon as well as Filley and others in St. Louis were very much abolitionists and were the vanguard of what became known as Radical Republicans, staunchly Union, very much believers in Federal republican supremacy at all costs to individual rights. Thus the willingness to use martial law or whoever has the bigger stick in the neighborhood sets the rules.
On the other extreme were the likes of Thompson and Jackson who were staunchly pro-slavery and believed in the theory that a state was independent and could just as easily withdraw from the Union of States as they joined, i.e a petition of the electorate of the state involved. Thus the failure of the State convention to pass articles of seccesion and what is more, pass a resolution re affirming the state's desire to stay in the Union was a crushing blow politically. Blair and Lyon failed to recognize it as it happened. The electorate had effectively shut the door on seccesion for at least 2 years.
Between these two polar opposites, I think the majority of the populace and military men sat. Even in the "centrist" middle ground you have a number of parties and positions.
Free the slaves but keep separate group included a number of moderate Republicans including Lincoln and Gamble.
There was a group of "state's nullification rights" folks essentially more democracy oriented than republican (note small letters not party affiliations but government contruct) and others.
It was this "centrist" or moderate group that was the majority and remember Lincoln lost the election in Missouri badly. One of the fears the voter of the day had was "What is a strong Federal government going to do to me and my livelihood?" Thus a position of neutrality was called for by the state convention and I think would have been held at least for a time. This was not a radical position and is almost identical to where Kentucky and Maryland were at the same time.
Price and Harney were old warriors well known to each other. A man's honor and word meant something. Price initially turned down a Confederate commission. He was a centrist at least initially. He did accept the position of leading the Missouri State Guard, a state owned and operated entity (not unlike the Ohio Volunteer Infnatry), not CSA, and it would not become CSA but instead disbanded with many of its units joining the CSA but many just fading back home to take up a guerilla insurgency in mid 1862. And yes, you will find many a MSG enlistee in the subsequent Missouri State Militia acting on behalf of the Union. The role as Price saw it, I believe and it seems validated by his letters to Harney and others early in 1861, was the enforcement of the neutrality called for by the dully elected state government and convention. This included protecting the property of the state as well as federal property and individual's property. Thus as a Mexican war hero well versed in the politics of the day he was highly regarded by the centrist majority population. As was Harney I believe, for very much the same reason. I truly believe Harney and Price thought they could keep a lid on things for a while longer in the state. Pipe dream, maybe. I also believe they both had a much larger worldview of the feelings of the polulace about the state than either Blair or Lyon did. I think Jackson thought he could convince or by braggadocio buffalo the populace into his camp. Clearly Jackson wanted seccesion. Price was a moderating influence. Jackson used in my mind Frost's naivete to pull on Lyon and Blair's strings in St. Louis. He certainly used the power of Governor to appoint the police board in St. Louis. Many a new German immigrant was unfairly "profiled", and more, at the hands of a strongly Irish and rather boresome police force. Into this mix comes the money and power of the Mayor and Blair and it is no wonder that the ethnic tensions brewed to a high level within the city. But it was that white ethnic non-slave owning poor folks strife that really overflowed into the Camp Jackson affair, not slavery. Yes slavery was a factor in setting the stage in Missouri but it served as a very poor litmus test of sympathy for Union or Confederacy particularly in 1861. As I've stated before I believe the majority of folks in the state at the time were glavanized into a position against the Federal government by Blair and Lyon's actions who would have been perhaps apathetic Unionists but at least not actively an opposing force.
Against this you can place the argument that who ever controlled St. Louis controlled the west and certainly the upper Mississippi valley and that Blair and Lyon's quick action saved the day for the Union. Perhaps I'm more cynical than I should be, but I've trouble giving Blair that much alltruism particularly watching his history for the rest of the war. Lyon I think was caught up in the glamour of the moment and perhaps unwittingly but very willingly allowed himself to be the instrument of Blair. His star was rising and tied very tightly to the abolitionist power brokers in St. Louis. Lyon was right to fear the loss of arms from the arsenal and perhaps his best decision was to move the majority of the arms out of the arsenal to Illinois. Harney knew that had happened, Price knew it had happened, it was published in the newspaper it had happened, so why continue the charade of "we must stop this militia gathering" that would have gone home in another 3 days anyway particualrly when Price and Harney got on the scene? Jackson and Frost rattled their impotent swords and Blair and Lyon took the bait to the detriment of both sides of the conflict.
FWIW
John R