I think the API already exists since you can use the phone app (e.g.) to control charging. I haven't looked at this for some time but while the API isn't/wasn't open it's been reverse engineered and I think there's an ecosystem using those APIs (not for this purpose but for other purposes).
EDIT: I think in my location all that has to happen for demand to shift is for the power company (BC Hyrdo in this case) to offer different rates. They can do this statically or dynamically and one way or another things will shift. As a person I can figure out to charge my car or heat my house/water or whatnot for a lower cost. I don't think they care.
We switched to a new power company purely based on rates. They offer free power for a 3 hour slot between 9pm and midnight.
We spent $2k on hardware to take advantage - a 7kw fast charger for the EV and a clockwork timer for the water tank.
In return we could load shift so much that 45% of our power is now free. That's with no other behavior changes (well one small change - family members became aware that having long hot showers in the day meant a lukewarm shower at night).
All super simple, and all driven from the bottom up by specific rates.
That sounds pretty great. I can't imagine my utility, PG&E, doing the same. Their TOU rates start at about the same as their tiered rates and go up from there. Even under maximal load shifting that plan costs me more than the simpler (yet still complicated) plan.
Instead it's more economical for me to drive my grid dependence to zero. I'm one of the "no thanks" folks in the article.
This is exactly the perverse pricing problem that Tesla (or someone else) can easily solve with aggregation+Autobidder.
Tesla knows your utility rate, including the absence or presence of time-of-use billing. They also have access to the real-time market behind the meter. In this position, they can always Do The Right Thing to minimize total cost of EV charging (electric bill minus earned Autobidder revenue).
In your case the Right Thing sounds like choosing the tiered PG&E rate, and letting Tesla aggregation pay you for load shifting.
I have no interest in letting Tesla, or anybody else, capture that value. Nor do I have any interest in propping up a failing grid at my own expense. I've been DIYing-at comically low cost-my way towards an off-grid electrified home. And I've driven up my energy consumption and quality of life dramatically while also reducing my costs and environmental footprint.
Looking at my data so far, it's cheaper for me to have a tiny gasoline generator to fill in under the quite-rare shortfalls (e.g., the two continuously rainy weeks in December where I don't quite charge up my batteries during the day, and I need to run heating overnight) than it is to pay the minimum grid connection charge.
I expect that as our local grid costs continue to skyrocket at about 4x CPI, and with distributed generation costs coming down, that many more folks will do the same.
It's fascinating how the economics play out. Thanks to this deal, it no longer makes sense for us to go solar or to have a house battery. So the power company has us as a loyal customer (at least, while they keep offering this deal).
EDIT: I think in my location all that has to happen for demand to shift is for the power company (BC Hyrdo in this case) to offer different rates. They can do this statically or dynamically and one way or another things will shift. As a person I can figure out to charge my car or heat my house/water or whatnot for a lower cost. I don't think they care.