They are all broke to ride, but have not been worked since 'Season before last' (I'm guessing summer of last year?)
From that quote I would guess it's been nearly two years since they've been ridden, and you mentioned one of the horses was 3 1/2 years old, the best he could be is very green broke, possibly only 30-90 days of training. Riding him would be like colt starting. Unless you have experience in colt starting, I would not even ask the owner about riding.
Herdbound, it seems you are an excellent confident rider, I really admire that, but not everyone is the rider you are. I lost all of my confidence as a rider years ago when I got on a horse for someone who needed a hand training, and it ended in a wreck because I didn't know what the horse's previous training had been(almost none). If these horses don't respect people from the ground it is very likely they won't respect a rider.