I believe the complaint was about the disingenuous denial of the plug.

How was it disingenuous? It is not a 'plug' it is a very relevant link. Being disingenuous would be to say "Hey guys, don't mean to plug my website, but here's my basket weaving blog."

I'm not gonna reply to you, but I really disagree with what you're saying and this is my response as to why.

Who. Cares. It's a colloquial usage of the phrase "not to". The clear meaning is that the writer acknowledges a potential negative perception, as a show of good faith, but still believes there's a valid reason to continue.

It's a definition thing. In my opinion it's still a plug even if it's relevant (and that's how some other people seem to read the word too here). So just come right out with it instead of doing the "hey not to plug my website but let me just plug my website" thing

who cares, it's useful at this time.

I don't think it was disingenuous, I read it more like... "normally I wouldn't randomly plug my website, but given the context, I think this thing I built might be super useful to someone".