I thought we are discussing 50+% nodes attack. With more than half nodes not cooperating in broadcast reliability is seriously affected. And reliability of transfer is far far away from time bounded broadcast.
Okay, okay, that's an
assumption. This assumption is stronger than those made by bitcoin. It's a start. Before, I thought that it's impossible to know the truth at all by passive observation, now it turns out that you need to disrupt the communication severely to prevent that. If broadcast is not working at all, the network is split and the situation is hopeless. If it works, but slower than usual, then we need to evaluate how much slower it can be made, how this could be prevented, etc.
The point I was making by analogy (was not about the viability of propagating the info to those who are online rather) is the "always-online" is about as far from reality as you can get. There is no way to relax from those who are always online to those who not knowing who to believe is telling the truth.
At least there is a grade of how long were you offline. The nodes connecting for the first time ever are the extreme case. A node who missed one message is probably easier to handle.