Why isn't Trump announcing support for Marijuana decriminalization?

It's an honest question. I'm genuinely looking to understand what the other side of it is. He can do it on conservative principles, it would take his black approval numbers higher, it would force Biden and Pelosi to support the opposite because they're mindless automatons, and he can easily spin it as a legitimate answer to the BLM movement (whereas the Democrat answer has been to riot more).

It feels like it ought to be a win/win, which makes me think I'm missing something.