If anyone else has a channel in the Ark and another outside the Ark they can be a bridge. If you are doing normal transaction in the Ark, *then* they are the payer. But if you open a channel to someone else who has a bridge out, then they are simply swapping Lightning with Ark channel balance and accepting that risk. And the Ark can only collude with itself until the transaction has been “settled” in the periodic closings that allow the Ark to get its old liquidity back. There is a gap where there is a collusion risk, but the cost of closing that risk is split up among all participants. It’s not magic, it’s just a huge batching system with a time delay to when the user is truly in control. I’d argue calling them scammers simply because it’s not exactly like lightning is a stretch, imo.