It sounds to me like a big part of the problem is that other people in your realm are perfectly willing to ignore the separation of IC and OOC to participate in his discussion.
In such a case, I'm not sure what else you can do alone. You could try reporting this to the Magistrates or the Titans, but I'm not sure that they really have jurisdiction over this sort of thing. (However, I do think it's a grey area at best, that could do with a test case...) Unless it's on Dwilight, I suppose, in which case you could definitely report it as an SMA violation.
This is, unfortunately, one of the problems with BattleMaster: when you get a bunch of people together in one realm (especially in that realm's leadership) who have no problem with people blatantly violating the separation of IC and OOC, and no problem with participating in doing so themselves, there's really very little anyone can do about it.