Also, you should note that the entire point of a carbon tax is to replace everything in your middle paragraph with something that's more intellectually-consistent.
Telling someone else that they aren't intellectually consistent almost never works. You'll almost always get a reply, "You're misrepresenting my statements, and failing to understand my argument" -- not a good opening to a good discussion.
I happen to agree with him that fuel cells are a bad idea, but I also think that if one is to advocate taxing carbon, they should be advocating the taxation of other emissions and pollution (if they are to be intellectually consistent). I have never heard Musk advocate for something like a battery tax.
I would be flattered if Musk ever replied to anything I'd said, and I am not trying to cause any sort of emotional reaction.
I also agree that 'just the carbon tax' would be more intellectually consistent than the myriad of other automotive propulsion policies Musk has advocated, but he happens to have advocated all those policies in addition to the carbon tax.
What are you looking for in a productive discussion? An apology because I might have offended the great Elon?
On the Tesla side, Musk has advocated subsidies for electric vehicles, taxes, caps, and other limits on gasoline/Diesel vehicles. He has argued that fuel cells are a dead end, and governments should stop supporting them.
On the SpaceX side, Musk has advocated open competitions for NASA, USAF, and NRO launches, but also encouraged the government to ban the use of foreign engines and rockets.