Scientific to the point of suspicion

If I remember correctly, these machines were constructed with the intention of servicing nuclear powered aircraft. Since some engine designs would become "hot" (IE contaminated) over the course of normal operation, and even if they didn't, you'd still need to replace the core from time to time, you needed a way to do that while shielding personnel from the radiation. The end result of this thinking? The closest thing to actual military mechs anyone's ever built. At some point, someone realized that maybe there were better ideas than regularly flying nuclear reactors above your own territory, allied territory, and the ocean. So this concept never came to fruition. But maybe, in some alternate universe, aircraft maintenance regularly involves mechs.