I think the Gyro-Balanced Khorium Destroyer should be added in the next phase of Classic BC. On the PTR right now you can learn the Tankatronic Goggles but not the Gyro-Balanced Khorium Destroyer from the information I found both of them were added in patch 2.1. I know that P2 BCC isn’t patch 2.1 but adding in some crafted stuff from that patch and not the others feels bad. Engineering as a profession is lacking far behind the others when it comes to crafted gear and I think that adding the googles AND the gun would put them closer to what other professions offer.
Considering that druids are getting swift flight form in the next patch I don’t think there’s a reason to arbitrarily hold back engineering when you are not rigidly following the patches anyway.
This is mostly self serving because I’m an engineering myself but I get jealous of all my friends running around with their fancy crafted gear. I just want to show off with a cool gun