Just having the same name or msn of someone does not make them an imposter. I could go to sythe and register as Allanon and not say anything about the real Allanon just because I like the name...
Unless he actual says "I am the Sythe Mod named R2Pleasent", then he hasn't done anything wrong.
As for anyone that gets scammed by him, that is completely their fault. As I always say, ALWAYS get a confirmation PM. If that means registering on sythe and getting a PM from him on there, then thats just what you have to do...