I think I am keeping up. I see the current coming into the 200 from the utility, going out the feeder to the 100, through a breaker, coming back into the 200 on the branch circuit taps and going off to the load. It returns on the neutral and goes straight back to the utility. The EGC is connected to the bus with the main bonding jumper. I see no inductive heating problems (300.3) and no ground integrity problems (250.4). That leaves me whether you are using the cabinet for a raceway and if there is adequate space (312.8).
I agree it isn't trade practice and it may be considered sloppy but I don't see a hazard or a particular violation beyond "I don't like the looks of that".
... but that is just the interpretation at the end of Pine tree lane, the only place where I am AHJ these days
