re: How about his pay for the last, oh, five years, can some of that be clawed back?
I think a better way is that any bonuses predicated upon future performance should be linked to *that* performance. Not the performance just gone.
If you knew your company had to remain in good shape for (say) 3 years for you to be able to cash your bonus, there's a good chance the company will be doing very well.
(see: Phillip Green)