I think this:
"If the release is declared no-go, the bug loses last minute status."
should be part of our policy. I considered it obvious, but I'm sure some people (/me looking at Frantisek) would argue. Let's put it there.
I am against prohibiting use of last minute status if a release is no-go. Kamil, we already have "bugs proposed as blockers 5 days or fewer before the scheduled" in the last minute definition, I'd that's say that's specific enough.
Also, we might want to preserve last minute "blocker waive" even if a release is no-go, consider having slip by one day (which is happening pretty frequently).