Like what?
I think it is possible that he is a little weird... or - more affectionately... "eccentric".
You posted that it was a slam piece, and I don't see it in what you posted.
All right, I will give you some direct quotes and comments.
The article talks about how has become a reclulse, and is basically hiding out in his house. Nobody has seen him, it isn't that he is tired after the movie, and wants to spend time with his family, it is that he is "in hiding".
From a "close friend" that they quoted, since The Passion, Mel is "post partum, or post traumatic, definitley post something".
After bringing up the same old stuff about the violence in the movie, they went on to talk about his next movie project being the Maccabees, and Mary Murphy questions "Why would he be making a movie about a subject like that"? After giving two possibilities, she goes on to say, "Or has Mel Gibson just become plain weird"?
Yes, I consider this a slam piece.