What Dan's proposing here is that Trending will become largely a paid-promotional area where the payment directly benefits the entire community. That's not a bad thing

I doubt that it would because relatively few people actually want to promote, and then few others want to vote, without receiving rewards. Yeah it happened in the case cited but its very likely to be an exception.

If it did becomes rampant then we could call it a problem but I'm doubting it.

The vast majority of the vote buying we've seen has at least part of its motivation getting the rewards back from the pool.