Well, for whatever’s it worth, I’m a former Army intelligence enlisted person, and I don’t find his “informed theorizing” very persuasive.
If it was a “probing attack”, what was with the warning broadcasts? I can’t personally think of any terrorist attacks, ever, that came with that kind of warning. The IRA would sometimes call in bomb warnings ahead of time, but that was itself part of the terror campaign. And those bombings weren’t infrastructure attacks.
This really seems to me like a personal grudge, maybe against AT&T, rather than a deliberate infrastructure attack, and even more likely an elaborate suicide.
Of course, I could be wrong.