Is it for safety or for collecting more rent. Certainly google can withhold installation till the new app is tested with their super duper Ai.
I think this was probably a very easy decision for Google after they weighed benefits and harms to users and developers.
I remind you that Ai can reverse compile and find viruses and crap and they could have tested multiple gazillion apps simultaneously even before Ai.
Being naive is one thing and that is fine but trying to advocate naivety is something else.
In my opinion, its about collecting new money and forced compliance worldwide to collect more and more. Every software company wants to collect rent from around world and that is why they are tightening their noose once their they know that they have some form of monopoly. It is not just mere accident in universe.