Wrong green! Haven't seen a darker green repaint on an Insight before. I wonder if it's an actual repaint or just a wrap.
I've driven several thousand miles with the battery turned off and it works fine if you cut one wire to keep the 12v charged at 14V vs 12.5V. MPG is pretty much the same except for in heavy stop and go traffic. Insanely reliable too; 260k miles and no oil burning or anything.
No AC in Phoenix sounds like a death wish, and AC compressors are expensive, unless it just needs the refrigerant refilled. Although you'd get better MPG with the AC off.
He also said nothing about transmission grinds, wet seatbelt issues, tires, etc. so there may be other problems as well. How far away from you is it?