This may be tricky, but see the attachment for what I mean. There's only one post on the page in question and by someone on an ignore list. My theory is either remove the page entirely, or show it with a "You are ignoring this user" notification.
This is a thread started by a non-ignored member. Said ignored member was the last poster and posted the post that started page seven of the thread. This is the end result. The thread list does hide ignored-member-started threads.
Removing the page entirely is basically a non-starter. And the page nav can't be changed to not show the page.
If we redirected you back to page 6 in this example, that would be very confusing to me as it would look like page 7 couldn't be accessed.
Right now, I think this behavior is about the best that can be hoped for (in a general case). I'd hope that with this, the "show ignored content" link would be more noticeable, giving an idea of what was going on.