1) The Tor Project still warns against maximizing or changing the window size.
2) Unknown if this is still a tracking vector for TBB, Whonix, Qubes-Whonix.
3) We've explicitly outlined that it is probably bad opsec:
(Do not) Maximize or change  the default window size setting.
4) It is yet to be seen if a patch has been introduced to completely kill this tracking vector.
So there is nothing to "um" about.
The fact is with possible risks, the user should resist convenience over security i.e. full size or resized screens, because it may be yet another unique variable to identify them e.g. Panopticlick and others routinely picking up screen size and resolution.
So, until The Tor Project removes the warning or it is proven this is no longer a viable tracking vector, the warning should remain. For instance, Mike Perry has noted there is an estimated 29 bit-identifier based on the browser and desktop window resolution information alone.
Re: Whonix users being more "sophisticated" vs TBB on Windows etc, based on questions asked in forums, stackexchange and elsewhere, that is a very dangerous assumption to make.