They aren't trolling and their shilling isn't off-topic, like i already explained to you, they manage to stay on-topic. As for zero/low value posts, you'd have to take that up with a moderator by reporting the posts, i am pretty certain they would not be deleted, because that as well can be subjective most times. Truth is there are worse posts than theirs in the forum, so theirs doesn't fall under the lowest of the lows as regards spam.

Make no mistakes, i detest their shilling and i don't know why an exchange would advertise in this way, but i am basically telling you why they are breaking no forum rules, which should be easy to understand.