Okay, this one may seem like a stretch, and is probably VERY unlikely, (and it probably contains absurd mental gymnastics) but hear me out on this one.

So Moe said He & Nigel found a couple old robots in a dump (which soon became Abe Grandpie & Burns Something I forgot his name), right? But he also said Nigel was quiet and Moe doesn't know the origins of these robots.

Moe also said Nigel was new to robots at the time, so he probably learned about the origins about these endoskeletons...

Speaking of, Suitcage's Fandom wiki page said the endo has a function related to souls, so perhaps Nigel got curious about the whole possession thing?

He tried to replicate the soul function via the Botsons, but he didn't want to get his hands dirty, so he hired Sideshow Bob to gather his test subjects, and that's where the Bully Group came in. But the project failed and Nigel abandoned it, leaving the Botsons to rust for the coming years until the New Krusty Burger location opened.

But we also have some counterpoints;

Sideshow Bob did murder one of Nigel's kids and Arlon's brother, so there's that. Nigel probably didn't want to work with someone who killed his own son. (Unless he was unaware it was Sideshow Bob but I feel like that's a weak ass argument).

Another huge counterpoint is that the Botsons weren't even possessed until Nedlyonette stuffed the bodies inside them at the New Krusty Burger...

(Maybe Nigel didn't think you need to stuff the body inside in order for the soul to possess the robot? Idfk. But that brings me back to my first point.)

Yeah that concludes my (dead on arrival) crackpot theory. I don't even remember how the fuck I came up with this. Anyways have a nice day hall see ya