I think disabling a feature based on search result count would be bad for usability. Search result count can go from non-zero to zero without any external intervention (e.g. because all tasks get done by new users, or by existing users, or something changes in how structured suggestions are generated) and a homepage module disappearing seemingly for no reason would be very confusing to the user.

On the other hand zero available task types can only happen because the wiki configuration was changed intentionally to not offer any tasks, so hiding the suggested edits module in that case seems reasonable.

There are things we might want to do when there are non-zero task types but zero task (e.g. not send notifications telling the user to try suggested edits), but I don't think disabling the module is one of them. We should instead show it in some disabled state, possibly, if that's worth the extra effort.