Rational agents in what sense? Consensus pool membership will not be a free for all and running a node will have costs, so we the only people who have incentive to run a node should be those who have an interest in seeing the pool succeed.

Of course, people who want to see the pool fail could run malicious nodes, but given appropriate membership restrictions and that fact that all an attack can do is pause the pool temporarily the incentive there should be pretty low.

Can you elaborate on this? I'm not clear what you mean either.