Thing is the Incubi controlling the Admiral Nagata is kinda in 'infiltration' mode. He's dodging medical scanner like a ninja to avoid being discovered by Kempeitei or Naval Forces medical teams.
So, if Nagata told his forces some unlawfuls would give them a hand, his men would start to question his orders and to ask themselves some things that wouldn't be good for Nagata.
A solution would be for SV to act undercover themselves. But that would mean them using a kusari lawful iff.