The military is not the secret service. If he was jailed they would likely isolate him from other inmates like they do with other high profile people. And he would have his secret service detail as do all presidents past and current as per the rule i quoted. In order to prove that theory true then you would need to explain how his protection goes beyond what is detailed in that quoted ruling. I really dont see a scenario where any secret service or military stops him from being jailed. That would fuel their accusations that he is above the law and the average person doesnt even know the theory exists, they would need a detailed breakdown of it and in this hyper politicized climate i dont see how any fence sitters would buy it. As i see it, him being jailed would set the precedent that all past presidents are not immune and can be tried for any alleged crimes. I really dont know if hes still president or not but i do know if hes prevented from being imprisoned after a judges ruling then it would be very very bad optics.