What if someone screwed up the programming of a conventional ham repeater
with the incorrect input frequency and clobbers a life safety operation?
Only the repeater trustee is responsible. The users would be responsible to know that they can't program an out-of-band frequency in their radios, just like they always would.
What if the repeater is part of a linked network and someone goofs up one
of the linked repeaters to transmit over a life safety operation? (Heck, in
the case of a relative of mine, what if your cable TV box malfunctions and
starts to clobber air band frequencies and you live near a military
airport?)
Can't happen. These things are NOT programmed on the fly. But again, only the licensee of the link is responsible for that.