I do believe you're on to something Edward. Yes, it sure does mean that there could be another reason. The next would be to avoid being a slave to the overpowering government. Same difference the Founders had with England.
The word, Slavery, was brought into every campaign speech because it was the hot button then. Now, the hot button could well be taxes, again. It's convenient to have a humanitarian cause tossed in with the real cause. Seemed to have worked for Lincoln. He really didn't care one way or the other til he saw the EP could probably get him some good press and a real fired up Army.

Pam