9S has been shown to be able to repair advanced machines, but he's not really an engineer? On the other hand, he's made for recon and extremely good at hacking/coding within that space. So I guess he'd volunteer himself for Computing & IT?

Honestly, he's willing to do anything the humans ask of him though considering he gets trapped in sidequest hell a lot. He's not going to vote for any leaders or anything, that's not his place, and he'll stay quiet as long as things are resolved peacefully.