I don't think they claimed to be Boston fans (I didn't read every word) - I think they are just Laker fans that think Red's Army is too harsh on them or something
nah, guy claims in the opening paragraph to be a boston celtics fan who is "striking back" against fake celtic fans who are hateful to other teams.
in the first paragraph he very clearly lays out that:
As a Celtics fan I’d like to congratulate the Lakers for what real Celtics fans see as a great season and an even better performance in the Finals.
note that here, and in two other lines he refers to "us" and being a celtics fan, but by the second paragraph, where he's ripping red's army:
That being said the dark side of Celtics pride once again found a way to report through those hate filled lens they soo love. Of course there “favorite to hate” Kobe Bryant got singled out in a post titled Best Proof Yet That Kobe Is All About Kobe. As like the litany of other Kobe Bryant hate that fuels the right wing Celtics fans it points a finger at Kobe Bryant as being selfish. They came up with this attack because during the victory parade Kobe apparently was wearing a Nike shirt with a puppet hand that had four fingers each with a championship ring on it while the rest of the team appeared to be all wearing some sort of white championship shirt.
notice that everything is "they" and "Them" now?
suddenly he sounds like a fan of a certain other team, and has switched from the whole "we, our team, celtics fan" motto of the first part.
also, whats a right wing Celtics fan? do we hold primary's and stuff? why wasn't i informed in our monthly newsletter!
Conclusion: Laker fan fakin' or red's army with a good parody of itself.