To me, his legs aren't all that bad, so long as he's not asked for too much. He should be fine for trails (at WTC) and parades, he should be fine for general ranch work (at WTC), he should be fine for walk, trot, canter in a straight line or on a fairly large curve. Please don't be afraid of riding him, he looks like a sturdy and usable horse. Where I'd be cautious is at a full-out run and quick sharp turns, because those will put more stress on any horse's legs. Anything where he has to plant a front leg and turn at speed- though of course he'll do that all the time running free. Don't enclose him in bubble-wrap because of our comments on one photo.

For me, that would rule out barrels and fast cow work. You could do poles and stuff with him if you do it at a trot- don't laugh- I had a dynamite trotting mare as a kid who cleaned up trotting poles.