Generally, if I have someone on my Ignore list, it is to prevent me from being provoked to an unacceptable response.
This usually works.
However, if I have a user on Ignore and they make a new topic, that topic, with their initial post, still appear in my forum feed.
I understand that some functionality is hard-coded into the forum software licensed from Vanilla. If it is possible, however, it would be a welcome improvement not to see posts from ignored users at all.