It's not Libre software. It's source available, which is great for a commercial product, allowing people to compile it themselves, but the license is revocable at any time.
It's not contributing to the open source ecosystem, so it's not part of the libre environment.
It's a good thing, I'm glad it exists, and I'm excited to see it spur libre development in the same vein. But it is not open source as the term is commonly used.
The difference with Linux kernel is that it's way more complicated to persuade someone who just likes the idea of it to install it, so there's really no protection needed - if you're installing a custom kernel (or more likely, a whole OS using that kernel) you probably know enough not to end up downloading malware.
That's not so true about just providing "random" APKs.
no need for a restrictive license! people can just take an apk and slap ads or malware on top. they do it all the time with fake candy crush apks. So I'm pretty sure they won't care about this license.
I think that in the license is just a excuse so no one is redistributing the app and they can make money from it.
I don't claim to know what their true intentions are. But if you want your APK with additional malware removed from any appstore, it for sure helps to have terms which don't allow ppl to do so.
There is nothing wrong about wanting to earn money, but their approach is the weakest. I did not even see a dialogue asking me for money yet.