4.5in "optimized" for one hand input/not willing to adapt UX to high density screen is a bad reason to sink your whole project.

i'd think a little harder about how one might "optimize" a flexible swipe-ui software to support a display all of 0.2" diagonal larger.. unless he's got a strategy to produce a smaller run for less $$Millions.

even worse excuse if they keep using terrible pinch-to-zoom gestures.