In that usage the object (football) ends up in the state of spiralling. So the HN title would, strictly speaking, mean that the magnetic fields are causing the black hole to spiral, which isn't right.

It's probably sort of being mixed up with the transitive verb "to circle", which goes the other way, with the subject ending up in a state of circling.

Is that so?

I was unfamiliar with football terminology so had to google it. Most references talk about "throwing a spiral" (noun), rather than "spiralling a football" (verb, transitive). But I can imagine this being a common usage. I have heard similar terms in other sports where you "verb" the ball, instead of throwing or bowling a "noun" :)

So I presume when a player "spirals a football" it means the player imparts a spin to the ball. (As opposed to player moving his/her own body around the ball in a spiral path :) )

Whereas the HN title uses it in a slightly different (second) sense -- "magnetic fields spiraling Milky Way's black hole" meaning something like "magnetic fields moving around / orbiting the Milky Way's black hole"

Semantics. literally.