I suspect he could have, but they'd still have to look after the prisoners (without anyone getting hurt or held hostage). To start with, detainment was against the treaty, and later on, given the SID have been kicked out of the building by the DoS once already, they don't really have a stable base they can be sure of. Idk. I guess less-than-ideal imprisonment would be a step up from summarily shooting them, but it's still... less than ideal. :-(

Yeah, it wouldn't be great long-term solution, but it might help while Haixing is actively being attacked (and the Treaty has been burned by then, so its stipulations are moot). I'm just thinking about what they might have tried to do if the Inspectorate and the SID hadn't been at odds, and they'd all made an effort to work together to contain things until Ye Zun himself could be dealt with ...