That's much more in your size. If it helps, I'm 6'2" and wear jeans/pants with a 32" inseam. That's not my true inseam for cycle fitting purposes, but hopefully a common enough reference. A 22" frame works for me on a MTB/hybrid. 20.5" might be just right for you.

The bar ends and especially the rack are good features on that bike. Sounds like the seller wants to meet in a public place. While that's a good idea, be sure he's okay with you taking a long test ride. That's easier to do when you're meeting a guy at his house and your car is right there so you will obviously return from your test ride, but it might make the seller uncomfortable in a busy metro area.

Good luck.