I agree, if you see a problem, even if he doesn't, tell him how you want your horses foot done, after all you are his paycheck, he works for you not the other way around. But it is up to you to do this, there's no need to keep quiet about it, this something that is very serious, when he trips he is putting loads of unnecessary stress on his legs that could cause him to go lame, not to mention the chronic pain that comes from having long flared out toes... You need to do some research on proper hoof shape. Hey, you may even want to print off some pics(of a properly balanced set of hooves) and be like hey this is what i want them to look more like...
Or if it all comes down to it, let him go as a farrier and learn to trim them up yourselves, most horses to phenomenally barefoot and it makes it easier to fix problems like low slung heels and long toes.. If not then id go with the first option if he is willing to work with you...Hopefully he is but, in the end, there is no excuse for letting a person other than yourself make decisions about your horses health especially his feet and especially if you disagree...
good luck,
hehe he has great confo though, lovely animal!
(oh and p.s. in the riding pics it is really clear he is having to overcompensate with his stride for those long toes, he is stretched out in the rear and the angles of his pasterns are nearly parallel to the ground, this means he is most likely very uncomfortable walking at all let alone being ridden, not trying to be mean, just observing!)