Well, I'd say it depends on what you are trying to accomplish.

If you don't agree with his political stance and and want to loosen his outsized influence on US democracy (e.g. by pouring hundreds of millions in political campaigns, silencing intra-GOP opposition by threatening to primary them with his money, using Twitter to push the fringe talking points of the day), then I would argue your goal should be reducing his net worth by refusing to buy from companies he's invested in.

If on the other hand, you're mostly criticizing that the quality of Tesla's cars suffers because the company doesn't get his full attention, it's a different story and your stance makes sense.