Don't take the below as picking on your post, I'm just using it as a jumping off point on the larger theme of 'how should we expect BB to talk about the Pats?'
BB is the GOAT of defensive coaches, and somewhere at the top of the list of GOATs of all coaches, across all sports. And we owe him huge gratitude for all her brought the region.
*And*... We've all been following this team for long enough to know that petty, catty and territorial is pretty much BB's default mode for anyone and everyone who is not deferential and/or useful to him. We don't have to wonder about how similar his motivations/behavior are to immature 7th grade mean-girl "you must all hate so-and-so because I do" lunch-hour-in-the-cafeteria snark. (The implicit message of which is that you should join him in picking on the same person he's picking on). Of course that's where he's coming from. He was like this in the 90s. He was like this when he first came to New England. This is who he is.
Look how he keeps shit-talking the Jets, for god's sake. The things that rubbed him wrong there happened two and a half decades ago.
I wouldn't hold my breath expecting him to get over his grudges with and about the Pats. Or stop taking shots at the franchise and the people who replaced him. It doesn't matter that Mayo was one of "his" guys. Mayo is not being deferential or useful to Belichick. He now sits at another table in the cafeteria. That die is cast.
This is not a guy who is going to take the high road, or be classy and respectful, or deal with people he has conflicts with in a mature way. There are people in his life that I know who have been waiting 40 years for him to grow up.
Belichick is in his early 70s. Life expectancy tables would probably tell us we got 10-15 more years of this.