We can consider this a good news, Tesla is one of the famous company/institution in the world. Having them on cryptocurrency world means a lot!
It is good for a short term but on a long term, I don't think so. Imagine if a lot of big fishes flock to the bitcoin market, the prices will go up definitely but in the long term, the small fishes wouldn't get anymore bitcoin because either the prices are too high or there isn't a lot to go for many.