[Zorutan]

That part about "goes back through the backend and, from there, rcons into the server",
I'm more than likely misunderstanding but wouldn't it be possible to execute any command there, not just rcon?

Because if so, then I could just make the server react to something like "/buy 1 1 1 20" when written in chat, that the player would say by replacing the rcon with a "say /buy 1 1 1 20"