In the US anyone who transfers crypto may fall under money transmitter license requirements. It is easy to get into trouble for running afoul of this and is one reason localbitcoins doesn't exist anymore.
what about bisq then? aren't they doing the same exact thing pretty much? if the government wanted to shut them down it would be very easy to sieze their domain name by giving namecheap a call and contacting cloudflare who is hosting their domain name. for a service that is supposed to be decentralized, it doesn't seem to be setup with very much forethought to being resistant to usa government interference! anyhow, i know bisq will try and get off on a technicality that they never actually get sent money to send to someone else. so they don't think they are a middle man or something. i am not sure that's a strong enough argument to stop government encroachment...