So that’s admittedly not a good look for canonical, but my read of that is that if you’re getting widely-known software from a developer who’s publishing it to snap themselves, and you’re cautious about your usage, snap is fine.
For example, essentially my only use of snap is to install certbot. If I follow the directions from certbot.eff.org precisely, then I’ll get certbot installed and no issues.
I certainly agree that (a) the system is ripe for abuse and (b) should be self-hostable to support Free software. Both of these could be fixed by canonical opening it up.
You might be interested to learn of the Fancyzones Powertoy which makes snapping windows to preconfigured zones quite easy.