not sure who would keep 8 million on bitstamp.
Seriously, anyone with that amount of money should
not keep it on any exchange, no matter how reputable it may be.
And yeah, I'd like to see some proof of this myself--but I don't think this is all that important in any case. Somebody with deep pockets might be moving their purchase to a secure wallet--smart move--or it could be any number of other things. But this isn't going to affect the price of bitcoin, and I'm not sure it really means anything.
If it is true that a whale moves his assets from Exchange to his personal wallet then I think that is the right step taken by a whale.
It's the right step for anyone to take, no matter how much bitcoin they have on an exchange. That's the first thing anybody new to bitcoin should learn: don't keep your coins on an exchange.