@Xerxes they’re trying to maintain a healthy player base, hence they made the server accessible by both Steam and Plutonium (prior to the latest Pluto build). Moving the server to Plutonium would cut out all of their Steam players and kill off the server.
As I say, not a problem for me (just others without access to an older Pluto build), as I can continue using an older build of Plutonium to access their server.
I can talk to their admins and get them to resolve the issue on their end if it’s not something Plutonium staff wish to discuss (fair enough if that’s your stance/policy), sure their server guys will figure it out in time so it’s accessible via the latest build.