By being made public they can be used maliciously by third parties. If such ISPs are slow to respond and reconfigure, they are a liability to the whole internet

By being made public they can be used maliciously by third parties. If such ISPs are slow to respond and reconfigure, they are a liability to the whole internet and the fault is theirs. A suggestion such as GPs, while probably illegal, sounds like an interesting way to hasten them a bit. Better to have their customers on their heels urging them to get a grip, than the whole internet in jeopardy.