Well, I think it's difficult to decide when it's appropriate to make comments and when it's better to shut up. The problem is, if you make such comments after losing, they will inevitably be perceived as excuses brought up by a frustrated loser.
Tsonga doesn't think about those reactions, he just says his mind sincerely, and deal with it.
As Fed once said :
For his part, Federer said he sometimes regretted his answers and how they were interpreted. But for the most-interviewed athlete in a star-driven sport, “that’s part of who we are,” he said.
“We are normal people,” Federer said. “If you’re not allowed to speak your mind, what’s the point?”
(source : http://http://www.nytimes.com/2012/09/03/sports/tennis/roger-federer-takes-on-news-media-interviews-like-pro.html?pagewanted=1&_r=2&ref=tennis
Besides, it was only one point in his interview, he also praised Djokovic very high (hence also the "resignation" comments some people made, but well you can be sure Tsonga will fight next he faces one top-4, just as Berdych did in the US Open after saying some "resigned" comments), the main problem with this kind of comments is rather that people extract one little point from a whole interview and speak as if it's the only thing he said and insisted on saying. Just no. He said it and skipped to something else, that's all.