My reasons are this, if all the equipment was still there, then when units were organizing in 1861, we should have seen an artillery company raised with the 4 guns utilized in that unit. The artillery was the creme de le creme of the military and upstanding planters and well to do's would have definately raised a unit to support that aresenal. The first unit however would be the infantry, Co I 3rd ARk Inf under well known George Alexander. Makes sense, he knew the people, they him, and he was by far the most knowledgeable man on military tactics probably in the area. He being a VMI grad would also raise infantry as infantry, with no attached cannon (as stated in many erroneous websites and museum regarding the Alger gun).
Also, look at the officers and NCO's... 1SG-2Lt-1LT-CPT Ben Allen (not a student of AMI), 2LT Henry Butler, Tulip resident merchant, not AMI. WHen looking at 1860 occupation listings almost all are farmers with a few merchants, bricklayers, carpenters but nowhere is anyone listed as a "student". Only one schoolteacher on the rolls...John W. Jones. In perusing the actual census for Smith township, Tulip area, if the school was still in operation, as you said, the students would either be listed as housed there or in homes. Again, in looking at the census I only found one student (I only scanned about 2/3 of the township but heavily on those living at Tulip proper) so this doesn't support school being active....unless, all students were at home due to break to work the farms etc if the school year was ran that way. But if we are to believe that the ranks were swelled with cadets and students to the stated number by websites and museum to 150 where would they be on the 1860 census??? They are not there and if school was in session, any school, they would have showed up in someones home or a "dorm" of sorts. Anyway, No listing of students show up on muster rolls for Co I.
Even though I don't have the documentation to state for sure what Mr. SMith said is accurate, I think that by looking at the actual census and CSR;s for Co I 3rd Ark Inf, the case can be made that no school was in session during that time. The unit enlisted in June 1861 and probably organized some before that. I would think that if George Alexander was the head instructor/superintendant of a military school, he would have listed that austere occupation over that of planter on the 1860 census. Also missing is MAJ Benton, who was his assistant who is also not on 1860 Dallas Co Census.
So after such a lengthy discourse, in plain terms, I strongly believe that AMI had indeed ceased to exist before 1860, and very probably a school still there in its place, the cannon and weapons returned to the arsenal in LR. I also strongly disagree with any statement that says the cadets all enlisted in Company I and marched off dragging their cannon behind them. If that was the case then there would be documentation on when the cannon were taken away from them somewhere in records. Of course, my evidence can only be based on interpretation of primary sources in the form of census and CSR's backed with secondary from persons who would have been around to leave record of events (Butler's etc). I cannot produce a primary document stating school was closed as military academy either. Based on my research of the time period, the organization of Arkansas forces in 1861 and others research... I am pretty confident Mr Smith is close to correct. Of course I leave the door open for my errors to be corrected if wrong. Nothing is certain except death and taxes!