nosferatu1001 wrote:"cover they are in" /= "in cover" - you asumed they are equivalent. Similar difference to "can not move" vs "will be moved" - similar words, different meanings.
The former requires you to be in something physical, the latter doesn't.
Cover is cover. It's defined on pages 21 and 22 of the
BRB. No where is it limited to physical terrain pieces. The hive guard implies terrain, but doesn't redefine what cover is for the purpose of the impaler cannon rule.