I've now read the GMP terms on their website, and I've moved closer to your position.
> They don't get a battery backup.
The customer in effect gets a "probabilistic" battery backup -- whatever is in the battery at outage time. As you say, the terms (para. 15) explicitly allow that GMP can use the entire battery at any time; it seems I was confusing those terms with different ones ("at most 36 times per year") mentioned by another commenter, which were actually for a different company, in NC. This is not as good as a battery that you fully control, and it would have been nice to see GMP place limits on its usage level in the terms, but it's much better than nothing, as made clear by commenter xoa and the customers interviewed in TFA. GMP wants high total charge levels in customer batteries, so their incentives are aligned with customers; the only potential misalignment I see is that it may not matter to GMP how that charge is distributed across customer batteries (to them, everyone at 50% charge may look identical to 50% of customers at full charge and 50% empty, but the former is much better from customers' perspective), but I also can't think of any reason why GMP would benefit from an unbalanced charge distribution, and maintaining rough balance seems straightforward, so I don't think that would be a conflict in practice.
> maybe get to draw power from it if there's a service outage (the company isn't obligated to let them use any of it).
This is simply wrong. Para. 15 explicitly obligates GMP to permit this:
> As Lessee, Customer’s control over the Energy Storage System is limited to its usage as a backup power source in the event of a power outage up to the point that the battery is completely depleted.
Outages are obviously "bidirectional", so there's no conceivable way for GMP to draw on the battery in the event of one anyway!
I didn't see any mention of net metering or payment for exporting electricity back out to the grid, which surprised me. Without such an agreement in writing, it seems unlikely that GMP would ever pay for this access, so I agree with you there.
The internet usage clause is reasonable and common sense, IMO. I suppose it would be better to include an upper limit to make sure that it isn't hogging the connection, but it would be my very last concern.
The only clause that I really disliked was para. 20, clearing them of any liability for damages caused by the battery.