That's a fine argument that they might have, but piracy still isn't stealing. If someone steals something from me, I am deprived of that thing. If someone copies my intellectual property, I am hypothetically impacted by loss of income, but I can still use that information.
They can say it's morally wrong for someone to use or copy information against the owners wishes or without paying. They are welcome to that argument. None of us are obligated to care about their opinion.
If they can claim customers don't own something, especially physical items, after purchase because they are being pedantic over how people interact with intellectual property, we can and should absolutely use the same distinction to distance piracy fromt theft.