I am not sure honestly. I believe he has a std size double with 130 BCD with DA 54t ring pasted to the outer position with inboard chainring removed. Translation? Crappy chainline with larger rear cog positions.
In truth, this isn't such a bad set up if he were to pick up a dedicated single chainring crank with chainline closer to the BB shell. Some purists believe and they maybe right that a 10s cassette with single chainring crank is too wide to run with anything approaching a clean chainline on the bigger rear cogs. A counterpoint to this is...it depends largely on how the bike is ridden.If big cogs are bail out only and not ridden on a sustained basis...then probably OK...tho not ideal.
Honestly I would consider a 1 X 10 on my personal roadbike. The reason I don't do it...is I ocassionally need the climbing inches with smaller front ring...big issue is, I prefer tighter cassette spacing and believe I would give up too much in performance to my aggressive riding buddies...the opposite of what the OP believes.