Well, we know he is, but that's /not/ what that means. When you "like" a post, it doesn't mean you agree with it or that you even actually "like" it. People "like" posts all the time that they don't agree with. The point of it is to amplify it or give it more visibility or maybe to make you speculate what you were speculating before.

If you want to know what Musk thinks of something, look for re-posts with emojis. If it's a good emoji, he likes it. If it's a bad emoji, he doesn't. If he "likes" it, it means nothing.