I have no idea if it's his real name or not. Quite frankly the question never occurred to me until you made such a point of it. As I said, I know people named Kermit, so there was no sense of incongruity. For all I know he adapted a frog sigil because of his name.
If that was the only criticism you had of his letter then it most certainly was an invalid one. This is not atypical of the dialogue presented by those without useful or relevant criticism. It is also a typical refuge to deny and accuse when called out on their lack of substance.
A letter representing a viewpoint generated from a forum thread, in response to a comment on that thread, and accompanied by the user names of the people participating in that discussion would have as much, if not more weight than names unrelated to the event, which is what RL names would be in this case.
The recurrent surges of new forum membership specifically to participate in this thread, many of whose agenda and ammunition is very narrowly sourced makes it obvious that this thread is well known to the FOA machine we are so constantly reassured does not exist. They will have no illusions about the provenance of Kermit's letter, or its import.
I, too, am graced with a name which was the impetus for no small amount of schoolyard taunts. Fortunately I was physically prepossessing enough for those taunts to be short-lived.
Nonetheless I managed to come away from those experiences with a sense that taunting people about their names was inappropriate behavior, and learned to avoid it myself. I'm sorry that you did not.