Perhaps, except the participants list is designed to give this kind of information and we don't want to go adding extra custom reports for every filter scenario. I think there is a strong argument to get this improvement in the existing interface. It's not grammatically correct but it should be understood what the filter does if someone selects it.
That being said, I think the alternate (and my preferred) way to getting this functionality would be to have students that have never logged in included in the results of the "Inactive for more than" filter.