Tom - If it were grounded I would agree with you based on your code reference of 250.24(B). But in the example Ernie cited their was no neutral load and based on the option to ground in 25020(B), he might not bond the wye SDS. If he did bond the system and also the utility Service he probably would end up with a 4-pole transfer switch with each system with it's own Grounding Electrode. (he could also use the same grounding electrode) but he would have to run the grounded conductor through a pole on the transfer switch.
IMHO or as I understand the code.
