I wouldn't say that they believe in a living constitution. That's a lie. They only say that to make their position sound reasonable.
They believe in dictatorship and that laws don't apply to the dictators. The constitution is designed to prevent that, so they hate it and ignore it and lie about 'interpreting' it in a softer, gentler, more modern way, while they burn it to ashes.
BINGO. They DON’T believe in the Constitution at all. They just can’t get away with saying their true opinion that they want to throw this outdated piece of crap out and do things OUR way, the RIGHT way. Except for some of the tenured academics, who can and do get away with saying that.