First, I don't know that he's ever used the patent, therefore it is possible the exclusivity of the patent has already expired. Most patents have a requirement that they be in use over a period of time or else the patent is considered unenforced.
Second, I doubt Mr. Dotcom has the ability to sue Google, Twitter, etc. As he says, he doesn't even have enough money to defend his own case. I doubt he would then have enough money to launch and wage a lawsuit against what are some of the largest companies in the world who either by cost, principle, or optics, would rather not get involved with Mr. Dotcom.