What Tom was implying is that Rossi basically fakes his playful personality, and that the 'real' self is something ferocious; he imagines that hanging out with people like him or Lorenzo would not be something so desirable after all, as it would be like being in the company of sharks.
Now I do not know about Lorenzo but regarding Rossi that's a wrong perception. I happen to have been around Rossi more than once, not as a personal friend (I'm not) but still as someone who was sitting at the same table and has been able to witness how he is, what he says, and how he behaves when he's relaxed and far from the cameras etc., and I can tell he's as funny a character as can be, 100% playful and unassuming, someone who really likes having a good time and enjoying himself in the same ways we ordinary mortals do. So in case you are invited to a pizzeria with him and his gang, go without fear. Only, if you are not fluent in Italian, you'll miss most of the jokes