I figured the term
extension as used in Drupal 8 does not exist here yet. So I felt it would make sense to map it as a synonym for module.
Surprisingly I noticed that module was already mapped as synonym for 7... Arguably module would not be a very good tag, as it very vague when it should be used. But wouldn't it make more sense to delete it rather than remapping it to D7?
Or was this to prevent others from re-creating it after deletion and was this the 'safest' method?