The reason for closing LN channels now is that you want to do it **before** there is a split, not after. It's preventive. This is important because otherwise you anyway have to monitor 2 chaintips on different clients and you might as well just let it sit.

The danger is only in there being 30% or more, but less than, say 75% of hashpower on BIP-110 in the first few days. If that happens, then there is a chance for multiple long reorgs, and that is where LN nodes are vulnerable. I'm not even sure how having a watchtower for 1 channel on each of the 2 tips works.

I think that the chance is small, but it is still non-zero. Maybe 1:100 that anything happens at all... but if it happens, we're probably not prepared.

optimism

What I really was talking about was the idea that things would become unstable on chain and in lightning. Everything seems normal besides maybe some LN channel closings. Also, the BIP 110 "game theory" idea about a sort of miner Byzantine Generals dilemma won't happen, if at all, until next week.