This turned out to be more ethical than I thought. I'd thought there wasn't any consent at all, or the actual mention of proxying was buried in a 20 page EULA.
Yeah, this does seem somewhat reasonable. I get that most users will probably accept it without thinking twice, but if you’re going to do something like this, this is at least a fairly upfront and consenting way of doing it. For the TV platforms where this isn’t allowed, you have to wonder if apps are still doing it but just completely secretly, and trying to hide their tracks as well.