Yes, this is exactly the kind of thing I was asking about.

I agree. If the coordinator also gets to dictate which relays clients must use, we're moving part of the dependency we're trying to remove into another layer.

Ideally the coordinator should coordinate the trade, while clients retain as much control as possible over how they reach the Nostr network.

That's actually one of the things I like about thinking of the coordinator as replaceable infrastructure rather than “the platform.”

Thanks — good point.