Jury might’ve had access on two fronts as both the son of the President, and also due to being apart of the Meek initiative. He had access to MeChips that granted him powers, which seems to be very exclusive, especially at the time. Also DaMeChip as brief of an appearance as she makes, works alongside to protect the Infini Regulator with Rexford in the Hero Project.
It’s not implausible.
Add to that the timeframe. This is when he shot Jenny, and thus probably on a massive guilt-trip. Regardless of how you treat Prodigal, the world knows you’re allied with her. Game should’ve provided more, but could see why a repentant Jury would try to help Prodigal at the time. Might’ve been wary, but could’ve been framed in a way that would’ve benefited the PC or help him get back at his father.
Also we both know Prodigal is pretty much a Mary Sue in regards to her powers. She can do anything with technology. She didn’t need to build her weaponry, it just appears. There seems to be some effort/thought into determining defenses and what not of the stuff she’s trying to dismantle or overtake, but her powers have a wide scope. There’s time-frames that can put this project during the novels, or even before. But doubt it’s beyond the scope of her abilities.
That’s not to say the story handled it well. Should’ve told us how Jury had access, why he did it for Prodigal, and a line from Prodigal of when they worked on it and why. Even if it was a ‘contingency’ plan for if things went awry in ‘The Prodigal’ or something.