Why would you want GCEA on a bari? It seems when I have tried the G C E A Aquila strings...both linear and reentrant, that it looses the full, rich sound found with the bigger body that they have with DGBE tuning. It seems to me to sound like a tenor that's just bigger and more bother to move.
Maybe he does not want to transpose or re-learn the chords names from C6 to G TUNING?
Also, due to the laws of physics, the baritone with a larger body (soundbox) will project more and be louder than a tenor, which could be a factor if playing often in a group setting and you want to be sure to be heard...
Another issue is that if floppy string tension bothers you on smaller scale ukes, the Aquila GCEA Nylgut bari strings on 19" are great, and even on an 18" scale instrument they are still good.
Further, when I tried normal TENOR Aquilas on the 18" scale (Zither Heaven 'tenor' banjolele), it kept snapping the A string, due to the tension being too high, but the Aquila GCEA bari set worked fine on this instrument.
Being a banjolele, there were not any signifivant bass tones to speak of any way, and in fact it sounds great with these strings.
So there could be a few reasons to try it. In my case it solved a few problems.