I also disagree with that, I trust my Linux distribution to behave well much more than I trust any Android platform and it doesn't even have much app sandboxing at all.
You can't fix a lack of trust like you have in Android with technical solutions. The flaw in Android is fundamentally a social problem.
That reads more as sports team flag wavey thoughts and feelings trust than anything actually backed by objective data.
There's a massive open source app ecosystem for Android which is far larger than the subset available in F-Droid. Open source does not imply private or trustworthy. Completely trusting applications with access to all your data with no insight in to what they're accessing or sending to services means you wouldn't know if your privacy is being violating anyway.