You can stop them from ever spending it. You can't take it from someone, but you can stop them from using it - I doubt most people would consider that much of a difference (they still suffer the loss).
This is true if you consistently have control at every relevant point in the future, but if a malicious entity gets control for a month and then loses it to the crowd again you can spend your old funds. That's one difference. Another is that the transaction log can theoretically be moved to a new chain if some part of the crowd desires (and has been), so if a proprietary ASIC manufacturer takes control the community, or some part of it, could move to a different hashing algorithm that isn't yet targeted by ASICs, and you could spend the funds on that chain. In either scenario you've probably lost value, but not all value as originally suggested.
Can you at least explain why you think with 51% pool control you can’t double spend ? It seems while not trivial you can approve and reject transactions/ mining as you see fit
You can't double spend -- you would need to generate 2 conflicting tx's with the private key. Only the person that holds the money can attempt a double spend, the miners only process and include (or exclude) transactions.
