The comic says that Master Mold was “designed” by Bolivar Trask. That also implies that he did NOT build it, just designed it. That dovetails with what little we know about Larry Trask and the creation of the Mark II Sentinels. The only other Trask who could have built it was Larry. That’s not reaching, that’s continuity.
Also, those panels make very clear that Casandra Nova was behind the Genoshan mutant genocide. Xavier’s evil twin did it, not humans.
BTW, Xavier’s evil twin Casandra Nova is presented to us as some kind of astral plane demon known to the Shi’ar. That she was able to create herself in a womb before birth and from Xavier’s cells makes her not just a demon, not just Xavier’s evil twin, but also a mutant herself. So, not only was the mutant genocide indirectly caused by Xavier, directly caused by Xavier’s evil twin, but it was also caused by a mutant, not a human.
Yes, correct, she did, in the very first generation of Sentinels. She played a role in the creation and design of the first generation of Sentinels. You can excuse that as her trying to kill just 12 specific mutants, to try to stop what she believes will cause an apocalypse, but she still played a role. Does her motivation matter?
For all we know, the Sentinels going crazy and deciding they will rule over humans too, as depicted in X-Men #14 through 16, was due to Tanya’s programming. We don’t know exactly what Tanya’s programming really did. What we do know is a couple mutants played a big role in creating the Sentinels. Period.
Larry didn’t know he was a mutant? Riiiight. To put it another way, Larry was a self-hating, mutant race traitor, in deep denial. He knew. Read between the lines of X-Men #58 or Avengers #103. Larry hates himself. He KNEW. Sure, he came around. But it doesn’t change that the Sentinels were developed by mutants themselves as well as humans.