Here is why Michael Kirkland isn't Redjohn:

Bob Kirkland asks Richard Haibach "Are you Redjohn?" And really, why would Michael allow his twin to be killed?

Why I think Michael Kirkland IS dead:

Neither Jason Lennon nor Reede smith recognise Bob Kirkland. Bob is checking if they think he's Michael.

So who is Redjohn?
To be honest I don't know. But I like this theory the best:
http://www.whoisredjohn.com/See-a-theory-Red-John/6373