they aren't saying they're banning partisan advertising, they're banning political advertising. a non-partisan political ad is still a political ad.
that said, just because a product is free doesn't mean ads aren't "selling" it, which exposes the flaw in my criteria: if you're selling a political product, an ad can both be trying to sell a product and be a political ad at the same time.
Oh I realize that they wouldn't ban my ad. I'm saying that the heuristic you suggested isn't quite nuanced enough. It seems like this move will create lots of controversy and actually make political advertising on twitter more fraught (because it will still happen, but just not above-board). This may end up being a net negative for society if it pushes things into the seedier underbelly (gaming twitter's algorithms so your tweet pops up in the ICYMI section, buying followers in order to appear more influential, etc.).
that said, just because a product is free doesn't mean ads aren't "selling" it, which exposes the flaw in my criteria: if you're selling a political product, an ad can both be trying to sell a product and be a political ad at the same time.