> So the only way they would have a legal claim is if I agreed to host it for them.... So the only way they would have a legal claim is if I agreed to host it for them.
You seem far more focused on right and wrong than on reality.
What you mean here, is *in your opinion* the only way they could win, is if you agreed to host it. Anyone can make a claim about *anything*, and it'll cost you to defend it if there's any possibility of it being found against you.
If you host a file called "jquery.js", notice Barclays are hotlinking and deliberately change it to include a crypto-miner, then you're very likely to going to end up paying to defend an action. It doesn't really matter if you would have won it if you go bust before you reach that point, does it?
> I can argue that they were violating my terms of service by linking to the file,
You can, but it's going to cost you money, time and stress to do so.
> If they hotlinked to a file and I changed it to indicate they used without permission, they could get angry. If I blocked their request, they could similarly get angry. If they felt the need, they could have their lawyers sue me for breaking their service. However, if I blocked, edited to print a string, or edited to introduce a miner, I have the same rights to do what I have done
The other side would argue that those are not the same thing. In fact, they'd argue that instead of introducing a miner, you could (and should) have blocked access, or even put a harmless change in to note it was being used without permission (as well as could have contacted them etc). Instead, you went for the path of most harm - and they'll claim that that was a wilful act and why you should have to make reparation.
> I have the same rights to do what I have done and they have no basis to win the case.
The very fact you've written "and they have not basis to win the case" strongly suggests you don't know how court cases *actually* proceed.
You won't find a lawyer who'll tell you a case is a dead-cert - they'll tell you that you potentially have a strong case (or the claims *seem* without basis), but that *anything* can happen once you reach court, and it's impossible to predict outcomes. In fact, a good lawyer will probably advise you to try and settle the case.
And all of this, is stuff that could be avoided by just not being a clever dick, and blocking access rather than willfully trying to screw up their users. There are an awful lot of things that you're allowed to do, that change with context and intent and suddenly aren't permitted.