Are you sure you don't rely on any third-party libraries that have been updated for security reasons? Are you sure there's no Android API being deprecated that you're still using?

I sympathize with the general idea that software that hasn't been updated in a long time is more likely to contain bugs and incompatibilities with newest OS versions. Whenever I've opened ancient apps on my iPhone or my Mac, they generally break either partially or entirely.

In your case I understand it might genuinely not need updates. But across the Play store as a whole, it seems like a largely beneficial policy. If there really aren't any dependencies that can/should be updated, surely you can make a tiny change to a text string somewhere, and get the added benefit of making sure your whole build chain still works? I get that it's annoying, but it really is valuable to weed out the truly unmaintained apps.