We can have both carbon taxes AND wealth taxes, of course. Carbon taxes seem to be an excellent way to curb carbon emissions, which is necessary, but they're also regressive, and unlikely to be sufficient to pay for the things we expect the government to provide.

PG may not be impacted by a California wealth tax, but that doesn't mean his opposition isn't self-interested. If it succeeds in California it could be taken up by other states, or the US as a whole - maybe wiser (in PG's view) to nip it in the bud.