Yes, i think there is a moral duty if you are presenting the software for the general public to use. Or if you dont to at least make it clear how you handle stuff so that users can make their own decisions.
> But there’s no contract with the free software developers. No duty of care from them to end users. Absolutely no duty.
In your view would it be acceptable to backdoor open source software to sell user's data to the highest bidder? That's obviously not what happened here, but seems like the obvious conclusion of your argument.