Nobody is role playing here. This thread seems specifically to be for the purpose of gathering people interested in RP to do so on MSN, with specific reference of acknowledgment that they can't RP here.
At the moment, there is no rule against off-topic in general (odd to have an off-topic board if that were the case), so this thread isn't any more objectionable than any number of other random threads active right now.
The purpose of a community is for people to be able to interact with fellow community members with similar interests. There's a rule against role playing, so these members are respecting that and role playing outside of the forum.
I can't really imagine what is objectionable about this thread that wouldn't apply more validly to other topics out there without complaint.