To be fair I don’t think this was known at first. He could have been fixing a perceived problem at the time. Post-facto we realize it was less important than many thought
While it wasn't known early on that it didn't spread by touch, it was known pretty early on that it spread through the air. Remember those people stuck on cruise ships at the beginning that all got COVID despite not leaving their cabins? It was entering each cabin through the air circulation system. They were sitting ducks.
To me, whether it's immoral or not depends on his attitude about it. People are misinformed, you have to go where the market is. If you're honest about it, that is, when asked, do you pretend your product solves a health problem or are you honest that it doesn't protect you from the perceived threat? If you're honest, "this won't protect you from covid", then you're just meeting a market demand. If you're lying, youre manufacturing a demand dishonestly. There are misinformed people in the world, and some stubbornly so, and if they're willing to give you their money even though you've made available information why they don't need to, I don't see a moral problem. Hopefully they learn not to touch the stove.