It’d be money laundering because money went in on one end, and money came out at the other end. Bitcoin would’ve been the vehicle yes. Still not money though.
Something doesn’t have to be money to be involved in money laundering, obviously.
Your legal analysis is very much incorrect. The U.S. will prosecute you for money laundering if you e.g. provide an illegal service, receive payment for that illegal service in bitcoins, then use a bitcoin mixing service, and then finally exchange your post-mixed bitcoins for goods. This is money laundering, despite there being no other money (like dollars) involved any step along the way.
In fact, the U.S. has prosecuted and convicted people for money laundering simply for operating the bitcoin mixing service, which is clearly just bitcoins in and bitcoins out.
