It appeared to me that the "third man" was looking at blocking a specific player and just happened to come along side of an already established 2-man wedge. Would we prefer that he didn't do that? Absolutely, but if they are not obviously coming together for the purpose of blocking (as a "wall"), then I don't think they want that flagged. As RR said in the CFO rules changes video, "we don't want to over officiate this rule".
Just my two cents.