Just like the Gonzales flag says, if the feds want their cannon, they can just come and take it.
Texas fought and won wars wars before joining the union, and would do fine after secession. The US doesn't have the will to fight just wars, let alone fight for a state that doesn't want to be part of the union anymore, especially if it will hinder the flow of food stamps. By your equation, the redcoats should have defeated the revolutionaries only because they were better equipped. When in reality, their hearts just weren't in it (and ours were).