Why should it bother Carrier as to what Flew thinks?
Because, as a wise woman recently said, "That is very shoddy scholarship for someone who's supposed to be so influential." That and the fact that Carrier has had actual correspondence with Flew, so there's a relationship there. Why shouldn't he be frustrated with him over this?
I assume you're trying to imply that Carrier is secretly frightened that (horrors!) God really does exist and now he has to stop participating in the daily drug-induced sex orgies that all us atheists must surely be engaging in behind your back? Hardly.