If they are spammy, you can remove the account as such by reporting it to support. I have yet to encounter this spam tactics. And itch gets abused right and left, but not with this one, as far as I know. Maybe it is rare? Or you meant something else with spammy.
Following a user is somewhat strange, and some people mistake itch for a social media site. But you do actually have a public collection and post frequently. An odd follower here and there is not uncommon.