We all thought the LML ECM was a Delphi too, just look at it!
I would be pretty confident it's a Delphi running the same or similar code to the E39 SIDI ECM as well, I can't see GM (these days) completely redesigning something to do the same job as something they already have.
It probably came down to cost or maybe Delphi didn't have an ECM ready to go with DI capability until now which is why GM has in the past used Bosch and the E39 (Continental / Siemens).