If you're allowed to create a hypothetical question that translates a hierarchy of guards into Boolean logic, then it doesn't matter how many guards there are.
"What would each of the other 49 guards would say the 49 guards other than them would do?" It would be a pain to do the deduction from all of that info, but it seems like it would be enough enough. Maybe it would make more sense to have that guard write down the answer (and throw in a pencil and a few extra sheets of paper)...