Out of curiosity, would this allow Google to perform the signing _at the moment of download_?

By that I mean, would it be possible that 2 different people download the app from the Play store, one of them gets an unmodified version of the app and the other (perhaps based on the user's race, country of origin, etc.) gets an on-the-fly modified version of the app.

The developer - and likely 99+% of all users - would never know or even be able to tell because most copies of the app in existence are 100% what the developer created. But, for a few rare birds, backdoors are aplenty.

Regardless, I'm 100% against this. But, my thinking above is this is possibly far worse than I initially imagined.