This does nothing to solve the malware problem on Android, because the malware is being distributed by "legitimate" vendors directly on the Play Store.
I get complaints of full-screen video ads in my ad-free apps from users who have never side-loaded anything. Malicious apps are launching them from the background, which is against the TOS, but technically trivial to do. If they get caught, they either call it a bug or start another company/product-line.
As far I can tell, Google promotes the highest revenue generating apps...so the dirtier the tactics you use, the more you succeed.
The bad apps do take a beating on reviews from legitimate users, but this is worked around by the developers posting massive quantities of fake reviews. It's presently somewhat easy to spot, legit apps will have reviews that are generally 1-3 sentences long, while fraudulent ones will have pages of 1-3 word reviews (often clustered together). Google doesn't seem to care though, as even some of the most popular apps are doing this to counter backlash from ever more ridiculously aggressive in-app advertising.
And then of course there's the problem that the average app today is so invasive of privacy that it would have been deemed outright malware ten years ago.