Not sure if that's a glitch as much as it is Bungie acknowledging that fusion rifles ballistics are energy based, hence the "enhanced battery" perk. While I do agree that they have way too much range, unless Bungie states otherwise, it's a functionality from weapon balancing. You may want to create a poll on that topic alone, as from my experience on here since launch day Bungie appears to take pills into consideration when they have high numbers in voting.