Basically there was a big thread by Zeddy a while back where he found that the Irontech Bomb actually has a faster fuse than its 5-star version (which had/has a Fuse on-par with BAB) while not doing that much less damage.
But when I got my own Irontech Bomb I tested it against my BAB and found their fuses to be the same (or if there was a difference I couldn't see it) and now that I've upgraded it to an Irontech Destroyer its fuse time still seems to be the same.
Did they change it while nobody was looking?
Depends on how old was that thread you're talking about.
Some Irontech and BAB changes were notified if you dig patch changelogs.
Could have been when they gave it stun.