I would like to point out that while this can sound like a good idea ( businesses have sales all the time, and offer certain things), I can see lots of problems. Not only am I opposed to free accounts in the first place, but why should those free account be restricted to people using IMC2 code? Either way, this seems like a ploy by the other company, and they may not be fully forthcoming, but I can't be certain. I know that my host had a sort of battle with another host(both fairly large) and ended up banning all connections from one to the other, destroying muds listings on the seperate servers.
I don't know the whole story, of course, but you seem to be doing good without something like this. Then again, who couldn't use more exposure, right? I duno, just ignore me.