Continuing the discussion from Exclude / Suppress (Automatically) Closed Topics from the Homepage?:
On a similar vein to the topic above, I would like to suggest that topics from suppressed categories be excluded from the “your topic is similar to…” list that appears on topic creation. We have a few subcategories that are used, to a certain extent, as archives - things like resolved bug/support reports, or duplicate topics. We hide them from the latest view as we don’t want users to scroll through them when looking at “active” topics, where we want activity, and in that sense have the same approach to them appearing as suggestions when a user makes a new post.
Understanding that not everyone excludes categories from latest view for the same reason, an alternate request would be to have another checkbox in the category edit Setting page, for “Suppress topics in this category from the “Your topic is similar to…” list”.