Like I said before, a missed investigation is better than a dead proved townie and already having the mafia he investigated.

If Buckbeak really is a Jailkeeper(which I'm still not sure of) then protecting Snape is the best course of action.

We may not have the investigation, which is random and might not be helpful at all, but we wouldn't lose a proved townie.

Plus, he can just start up the investigations when the heat(so to say) is off.

I, for one, do not want to see Snape at the bottom of the pond tomorrow.

And an investigative role that learn the entire role is a great asset.