The dent is almost the width of the tube and maybe almost a cm deep. The crack is horizontal in the center of the dent and extends out of it to over halfway around the tube, so I don't think there's really any strength in the tube there. The opposite side of the tube is fine and straight, and everything else seems straight and undamaged. I just assumed it hit something hard at that specific spot and that was why it was tossed, but maybe the crack showed up after the dent or slowly grew longer.
I've never had a big tubed aluminun frame, so I was impressed with this one. If I saw this kind of damage on a skinny steel tubed frame I don't think I'd think of it as possibly ridable, but this one just looked different to me.
I have good (but heavier) bikes, so this would just be an experiment. It's an interesting frame and very light but I do wonder how it compares to the new $99 ones available, not that I'd buy one.
If I do try riding it, I'll probably at least try jamming something down through the damaged area. I guess this would involve drilling out the water bottle mounts and hopefully a dowel or somethinig of the right size could push out the dent on the way down.