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.