The right thing to do clearly is to release an anodyne official statement, then to leak all the "he wasn't up to it/he didn't have a clue/he hated Paul Barber's long, boring emails asking for more theme night suggestions"-type dirt off the record immediately afterwards. That way everyone's happy.
Did he? What reason did he give for sacking Poyet?
I think the point here is that genuinely reassuring communication might need a bit more substance to it than "just keep calm (and keep paying)".