The only way to stop tyranny is strict opposition. To include a secession amendment would in fact tell them, if you persist, then we are not playing your game and are out of here.
Secession need not be violent. That was the fatal mistake of the south when they did it. They made it violent in the beginning. Even US Grant said if they simply would have said “we cant live with you and wish to go our own way”, he would have supported them.
To play with evil by legal means comes to no end. At that time, words mean nothing.
I would agree with a secession amendment as it is a routine inclusion in any contract for the parties to agree to a method of enforcement or dissolution.