This is a type of spam we’ve seen from time to time. Often something vaguely related is posted (might actually be a copy and paste from a similar topic… though now AI might be easier). Then the account may come back later (sometimes after a very long time!) and edit their post with a spam link.
I don’t believe we have a way to filter for this kind of case… maybe we could identify when an inconsistently active account comes back and adds a link to a post? (If someone posts, disappears for a month+, and then returns to edit a link in?)
One option you can utilize in the meantime is locking their trust level to 0 or 1 (from the user admin page). This would prevent the account from coming back and adding links to posts (or making any edits) after 24 hours. The downside of this is that it can limit someone if it turns out that they’re not a spammer.