Single arm DB press is great & i bet a strict one you would not press that weight. Not against full body exercises but itīs not like a true strict press is it. If doing strictly delts i see no need for it. just more of a cross-fit thing. Maybe that is your goal i donīt know.
Depends on what you want out of it.
I used to do one arm DB clean and presses all the time. Made me stronger on the more static lifts.
SC is a strong dude, i think i used to work up to 140 and i've never seen anyone other than strongmen do more than that.
I could probably do the 100's today if i really worked up to if for a few weeks, but my shoulders are shit so that's going to be a hard no attempt.
But you're not wrong, a strict standing one arm overhead press is a very difficult lift. I used to love doing them because they make you strong as an ox.