I'm inclined to think that that's more a bug on their part since Ctrl+K isn't one of those unstoppable key combinations (Ctrl+W, Ctrl+Tab, Ctrl+T, Ctrl+N, Shift+Esc as far as I'm aware are the only ones). Perhaps they just aren't calling e.preventDefault() on their event handlers.

And even for the combinations which can't be captured, the new Chrome platform app API lets you stop those.