In the case of a software updater, I think "not updating" is probably correct behavior. Broken behavior would be the app crashing or misbehaving or throwing errors because it tries to update the app on read-only media.
The author's concern is that they (and many other developers) ship apps in zips, have many users download them, and run them from ~/Downloads/ or wherever their browser downloaded the app to. Only in 10.12, this practice will prevent most 3rd party apps from being able to update themselves.
The author wants an info.plist key (plus perhaps app signing) to opt-out of translocation and say that they are competent enough. Before thinking that this "defeats" the point, people may miss that Apple is fine with opting out provided you code sign and package a dmg.
The author and many others also don't like dmgs, however, and find that they confuse many users. What the author is concerned about does indeed affect a lot of apps.
(I really don't know if that many apps do this btw, I think most apps I download today are packaged in zip..)
Other users are just baffled and run apps from disk images or Downloads just because.
The authors point is that at least before 10.12 zip was a decent approach.
Too bad they aren't offering signed zip or something similar that takes same advantages that a signed dmg does..
The Info.plist approach (where the app declares that it has no such relative path dependencies and so should skip gatekeeper path randomization) seems like the best approach for fixing this "issue".