The Eleventh Mechanized Cavalry Cluster fought in Operation SCOUR, and fought on Mars during the fall of Terra at the end of the Jihad. Given that the Master's hideout, ROM's training center, and one of the primary Celestial factories were all on Mars, there's adequate reason to believe that one or more Gestalts were present and the Horses salvaged one. The R&D start date given in IO Beta is 3082, which is pretty much what you'd expect if they'd salvaged some of the tech on Mars in '79 and sent it back to the Horse OZ. If anything, given that the Bears were famous for utterly annihilating anything Blakist they came across, and no Bear ground forces participated in the assault on the Terran system, it's less likely that the Bears got their hands on any working copies of the tech.