Unless Blizzard says it’s a bug, it’s not a bug. Until they say that, it’s a feature.
EDIT: This was reported 4 YEARS AGO https://www.reddit.com/r/starcraft/comments/2yqewu/broodlords_have_the_same_range_as_a_siege_tank/
The likelihood of this being a bug is in the 1% range.