Maybe. But then again, an average fit man is often too heavy for many horses. I mean, ideal weight for a rider is 10-15% of the horses weight. A real horse, no pony , weighs around 450-600kg (some a bit more, but if a horse is fat that's extra weight on the joints too). So max weight on a horse on the bigger side is 90kg but many smaller horses don't cover riders heavier than 60-65kg. Looking at this picture, the horse is not small, but it has a long back which usually means it has a weak back and should not carry too much weight.