It's not like the BG's specs are common knowledge, anyway; the warehouse would be under clearance and need to know restrictions. And the people working there, under NDAs.
I have always thought that the entire BG program must be a massive disinformation campaign to instill fear of the technology in the 3I's neighbor polities.
In this way, BG tech is much like the Darrian Star Trigger (except that it does actually work): more useful for the strategic uncertainty it generates than any practical, tactical applications.
Thus, the always-unimpressive
Kinunir patrol ships were built to make public use of the technology (it is, for example, great for stealth applications such as the clandestine delivery of Imperial Warrants), while the Agility-5-you-must-be-kidding-me
Atlantic-class proper cruisers had their BG fittings "plated over" before being gifted to client states the 3I wished to coerce into allegiances.
Even the absurd
Lightning-class Frontier Cruiser refits were little more than a demonstration platform to make sure the Zhos were properly respectful of the stealth applications of the tech.
Have you ever seen what PCs
do if you let them get ahold of a BG? Corsair Legends, they aspire to become. Until they get cocky and blow themselves up, of course.
I have always seen BG tech as an "open secret" in the OTU, more of a political tool than a military one. So much pretense goes into keeping it "classified" while the other hand carefully shows off its existence to anyone keen to take an interest. The only real secrecy is maintained around the early progress that has been made in reverse-engineering the tech, and in insuring that BGs are destroyed if the ships carrying them are combat causalities (which is a fairly trivial, albeit suicidal, process; it could even -- ahem -- be automated with the right software).