I think the jury is out on whether lower taxes on dividends and capital gains is a net benefit to the economy, as both tend to favour wealthier people and the logic thus relies on the trickle-down theory of economics, which has been more or less debunked.

Not the least reason of which was what happened when Liz Truss was in charge. The outcome was rather unpleasant results for everyone except a few people who bet on the pound taking a nosedive.

So yeah, I'd still tax him more.