Sure but the update can already have done some stuff, leaving your machine in a half-updated and maybe corrupted state. If downclocking doesn't work there really isn't a good solution here.

Edit: oh wait there is, DON'T UPDATE WHEN SLEEPING. And on top of that, just don't update without my explicit approval at all. Thankfully I run linux where, if it's not the default already, it's a config value away.