I think his point was more about the GUI technology, instead of the GUI layout. The GUI does not behave very well on HiDPI screens with scaling.
This is what I sounded like when I was trying to convince my non-nerd friends that they should use Linux on their laptops. People have different requirements. If a modern interface that isn't blurry on modern screens is one of those requirements, then so be it. Convincing them that their requirement is wrong isn't going to fix GIMP