If all PS exploded it's not interesting case. It's trivial. No PS, no elerium.
About explosion of PS you contradict yourself.
In vanilla Xcom possible several cases:
1. Exploded only left PS. In vanilla Xcom it kills the middle PS. Remained only right PS and 50 elerium.
2. Exploded only middle PS. In vanilla Xcom it kills left and right PS. No PS, no elerium.
3. Exploded only right PS. In vanilla Xcom it kills the middle PS. Remained only left PS and 50 elerium.
4. Exploded right and left PSs. In vanilla Xcom it kills the middle PS. No PS, no elerium.
5. All PSs stays intact. 3 PS and 150 elerium.
The conclusion:
If some PSs left, then possible only three scenarios in vanilla Xcom: only the left-most PS left, only the right-most PS left, or all 3 PSs left.
You confirm it. It's good.
yes, IF SOME are left, there are only three possible scenarios, but that doesn't mean that none remaining isn't also a possibility. think about it for one second: if each power source has a 75% chance of exploding, there's a chance all three will explode. the sample they are talking about excluded that possibility, but that doesn't mean it doesn't exist.
In the another hand, in OXC possible several more situations:
6. Exploded only left PS, but middle PS is not destroyed. Remained 2 PSs and 50 elerium in right PS.
7. Exploded left and middle PSs, but right PS is not destroyed. Remained 1 PSs and no elerium.
8. Exploded only middle PS, but left and right PSs is not destroyed. Remained 2 PSs and no elerium.
9. Exploded only right PS, but middle PS is not destroyed. Remained 2 PSs and 50 elerium in the left PS.
10. Exploded middle and right PSs, but left PS is not destroyed. Remained 1 PSs and no elerium.
You said:
it's a possible situation in vanilla too, it's easily confirmed, hell it's included in the data table, it's literally the first entry.
But this is contradict your words above.
Cases 6-10 impossible in vanilla Xcom.
It's never happened to me. It's never happened to you. It's never happened to anyone. It's not described in ufopedia.
It's just a fact.
The conclusion:
If some PSs left, then each PS filled by elerium in vanilla Xcom.
Explosion in OXC is not 100% identical with vanilla Xcom.
Explosion in OXC has a bug by design.
By the way, in my opinion not 100% identically is not a problem in this case. Because the bug has easy workaround.