If I was running a nostr relay, I would consider it spam and I would block it, unless I uploaded it to my own relay, or charged some money for it. Anyone who runs a nostr relay and wants to do something like that can put a filter on kind number 57009, which is the kind I am using for this.

To me, that's the beauty of nostr: it's not up to me. Every nostr relay gets to pick and choose what they think is spam and/or what they want to charge for. Nostr puts the relay operator in control of their own relay. And this app abides by that by specifying the relay to use directly in the image id. That way whoever is using it can connect to a relay that you know has that data (or at least had it at one point).