This conversation is more suitable for a LN-specific thread and for people who know more about LN low-level security constraints than me, but I'll just point out that the deadline for closing the channel is not one block, it is whatever period of blocks you put in the funding transaction's timelock. If you see the main layer become more congested, you do it earlier at a safe distance from the deadline. You could, for example, have a rule of opening channels for two weeks, but always closing and reopening the channel 24 hours before it expires. That said, I agree with you, in the process of maturing, LN has a lot of things to take care of, including this one.