I don't use Emacs myself, and I don't recall a single Emacs user complaining about accidentally triggering Ctrl-Alt-Backspace on their way to M-C-E-A-S paste-output-of-doctor-into-irc. Most of the grumbling came from actual users (i.e. people who don't know what an X server is, let alone how to configure it, let alone to email xorg-devel@ about it), rather than people who are perfectly capable of changing the default[0].

Regardless, Peter came up with a perfectly sane plan which makes it very easy indeed to optimise for clients with stuck grabs (being that termination requires you to be processing input events in the first place, in which case you're likely doing reasonably well anyway).

[0]: Yes, the text is woeful. Sorry.