No, not at all petty. Kudos to the developer for standing up to the bullies that Apple and Google (and other tech companies) often are. Apple really needs to be

No, not at all petty. Kudos to the developer for standing up to the bullies that Apple and Google (and other tech companies) often are. Apple really needs to be reminded harshly that it is the developers that add value to their platform. And to share another perspective, I never use login from another service as it means you are sharing more data with them, and you become hostage to their whims and fancies they call their "terms and conditions". So if one day they don't like the app / service you have been using for whatever reason, they can bar you from logging into it without giving you any choice for it.