If they are demanding discord for communication up front and not advertising on the same server...then NO...it is likely illegal RMT.

Good luck proving it.

And to anyone who says otherwise...walk away.
The obvious fact they are demanding outside communication alone and not on the same server should be screaming suspicious to you guys.

This has been argued ad nausea beyond all reason over the months.

Good luck getting SE to lift a finger. (Evidence accepted/not accepted clause) As anything OUTSIDE the game is refused.

Gee I wonder why that is. (rhetorical question)