The term grey zone (regarding third party tools in general) was used unless you disagree with the translation of this interview: https://www.youtube.com/watch?v=e_i6mjiGerU which you might but since I dont speak japanese I cant comment on the correctness of this translation.
I have watched the interview basically every time a thread like this pops up because there will always be someone (you in this case) assuming that I didnt. The UI modifications currently targeted are very minor and the actual advantage it gives is questionable at most, nowhere near many legit advantages some players have over others. Does that mean I am on board with all of them, obviously not but that's not the issue at hand. The issue should always be focused around "is this player causing a problem?". ToS are a tool to consider in that question but can never be the sole authority.
The problem SE sees with ACT is not that it's a third party program but that it could very easily be used for harassment. He says that pretty clearly. If the only problem that exists with ACT was that it's a third party program (and absolutely nothing else) then SE would have implemented a parser. This is what I mean with something cant be bad because it's illegal, it has to be the other way around. I agree on their stance that an endorsed parser would absolutely be used in toxic ways, that's why I thought the way of handling it was the correct one, even if that way introduces other problems.
How rules are applied (or if they even are enforcable) matters far more than what is written. SE does not care about parsers, not because they dont want to care but because they cant care. They dont care about UI mods, not because they dont want to care but because they cannot care. SE does not care about pvp and gathering bots, not because they dont want to care but because they dont care for the arm's race that would be kicked off by it. What SE actually cares about is their bottom line, they are a company and a quite greedy one at that.
What I think people need to realize is that the bans handed out now against streamers are entirely performative. In the grand scheme of things this is a storm in a teacup. I dont know how many people have been banned because of report brigades by now (a thing yoship has very clearly spoken out against in that LL) nor does it matter. If 3 people either dont stream anymore or hide all modified things from stream then that does nothing. Nothing of value has been achieved and nothing of value will be achieved by these reports.
What I am actually concerned with are hyper toxic forums like 5chan. They provide nothing of value to the game, the only thing they can and want to do is to destroy. The game wont be better if they get what they want, they'll just look for a new thing to destroy. They'll forge evidence if they have to. People like that can be obsessivly dedicated.