It's their choice until the inspector chooses for them.
My "their choice" was aimed at the part of their decision making process to implement that 'solution' for their distro cabling.
The essence is in Ray's post. Using 2 AWG 4 conductor unitary jacketed cable with single pole, separable connectors (i.e. Cam Locks) is not permitted by NEC but that doesn't keep folks from doing so, at least until an inspector comes around.
Pretty much what I meant to say as well.
I can't make people do things the exact right way (cabling, pulling a permit for generator, having it inspected, etc)-- all I can do is make sure that everything I am involved with is abiding by the code. If a provider/client/whomever-calls-the-shots hasn't pulled a gennie permit, an inspector isn't going to come around since they don't know about it. If I am providing cam feeder for them, it'll be single conductor runs, you can be sure of that! (I am also anal about color and labeling. All new cam I build, I am ID tagging both ends with length and CompanyID#, so that I can always figure out which cable is going precisely where.)