I want to defend Mef this way: I'm a believer that the engagement of the crowd can affect the game on the court. Earlier this year, if I remember, both Kyrie and Brad were talking about the affect the excitement of the crowd had in their comeback win over Golden State.
The most pointed example of this I've seen was in Brooklyn, when the Celtics were visiting the Nets last year. I went to that game and the crowd was... thin. There were as many green jerseys as black. The energy of the crowd was the lowest I've ever felt at an NBA game (the only other live NBA games I've seen have been in Boston, so...) and the product on the court reflected that. It wasn't a great game.
Not that the players weren't trying but without crowd energy to feed off of, they all had to manufacture their own energy and it just wasn't the same.
This is all to say that Celtics "fans" who show up and don't engage with the game are, however small, a negative influence on the team that I love and so I don't want to see that at the Garden.
I write this, fully aware, I am a pretty cranky dude.