I'm not familiar with US legislation, but from my perspective this is just Musk on his soap-box making a statement. It's not something I can rely on while building a business that possibly (!) infringes one of Tesla's patents. They may retract their statement and reconsider at any time, especially when times get tough.
It's nice to hear this, sure, but I fail to see the meat in this announcement.
The question is whether its a specific enough statement as to reasonably induce reliance, and whether promissory estoppel would apply. It seems to me (and I'm not an expert) like it may be close enough as to seriously threaten Tesla's ability to successfully prosecute suits, and vague enough that anyone else would still be leery about using anything Tesla has patented.