"So if the FCC, FTC, and Courts hold it isn't a violation for T-Mobile, it follows that it isn't a violation for the big US providers either."
No, sorry. Antitrust has never worked like that. It's triggered by market share, and evidence of market distortion. Always has been. No Court has ever followed that logic.
See my a) b) and c) above. BingeOn just doesn't trigger competition issues. The fact it triggers a witchcraft panic tells you more about the witchhunters than it does about the nature of the witchiness that they object to.
I've listed things in the past that the US consumer can do to get a better more competitive market. Competition legislation is definitely one of them, particularly at the state level. Organising mass switching is another - you only get better service if you threaten to leave. People seem to be too lazy to do this and wish the Gubberment would just wave a magic wand and fix everything.
So this is all about control. The absence of rational standards for fighting anti-competitive behaviour, and the insistence instead on random witchfinding, means Net Neutrality is becoming a revolutionary cause that is devouring its own children. No Net Neutrality revolutionary wants to be seen to be 'soft', and face be denounced by his comrades as a sell out, so the onus is on finding witchiness in places nobody else has yet been able to find it.
Where strong Net Neutrality has been passed, ISPs can't differentiate themselves on speed or quality (bad, illegal, burn the witch) so a bad market becomes even worse. We know how this story ends.