They already do. Outside of tiny companies the norm is block all AI across the board if they have the IT staff that knows how. From what I've seen, large enterprise companies are still testing the waters outside of dev/IT use.
Patently false. The mag 7 all use AI extensively. I'm part of another 300k person company who uses it extensively. We have been slow to allow it as we come up with enterprise contracts and policies and figure out if generating code jeopardizes our copyrights, but the company as a whole is encouraging use of AI.