That thread is full of FUD (Fear, Uncertainty and Doubt) over an incident from 2015 when there was an integration (now removed, in a desktop environment that is no longer used) that would allow you to search amazon store from your desktop.
Ubuntu is just as trustworthy as any other major linux distro.
I read here since more than 6 months but when I saw ReCaptcha I did abort the registration at the forum. ReCaptcha is really terrible and I also try to avoid Google services. I am still not happy about Akismet but willing to accept it which is the reason why I did now finish the registration.
It is very exiting and awesome to see what happens at UBports to get the choice not to use Android or IOS and get back some privacy.