You have to go a long way out from the concept of Boltzmann brains before “inability to have any coherent thoughts” ceases to be overwhelmingly dominant in probability to the point where you can’t even reasonably estimate how many orders of magnitude of zeroes precede the first nonzero digit in the probability of the rest.
Realistically, if this isn’t a fundamental property of whatever you’re talking about, then you’re not talking about Boltzmann brains at all.
You have to go a long way out from the concept of Boltzmann brains before “inability to have any coherent thoughts” ceases to be overwhelmingly dominant in probability to the point where you can’t even reasonably estimate how many orders of magnitude of zeroes precede the first nonzero digit in the probability of the rest.
Realistically, if this isn’t a fundamental property of whatever you’re talking about, then you’re not talking about Boltzmann brains at all.