I still think that once the payout is made the hashrate is effectively distributed to the various miners and that the pool owner no longer has 51% so no attack is possible.
Now if the pool owner suspends distribution that may be a different story.
That doesn't mean that a fork isn't possible, it just can't be maliciously used.
And I still believe you don't get the problem. It's not about the pool owner being able to "control", i.e. own your coins, i.e. detain the private key of the new address they're at. It's about being able to use them -- or any other of your coins for that matter, as long as he knows their addresses -- as inputs for new transactions that MUST be accepted by at least ONE miner to get into the block chain.
If 90% of miners are rejecting your transactions maliciously (i.e. disobeying protocol by excluding them, but still producing technically acceptable blocks by all nodes following that protocol), and ALL blocks produced by the other 10% are rejected by the 90% (again, maliciously, disobeying protocol, but technically he can), then your coins are effectively embargoed: you still own them, but you can't use them.
So your coins are effectively worthless at least until the situation changes, because until then, none of your transactions will ever get a single confirmation on the whole network (or they'll be orphaned eventually)