Look through any big bull sale catalog, and you will find a large number of bulls that are in the mid to upper 90's birthweight range. They sell fine, people look for them. If my cows can not lay down and have a calf in the 90 pound range unassisted, they get a ride. I would NOT expect a dexter to do that. But MY BREED does it daily, without assistance. There is a direct correlation between birth weight and weaning weight; smaller calves wean off lighter. People who buy bulls with bigger birth weights are looking for that. To much is lost if you use a calving ease bull for your cows.
With that said, Ron does have larger than average birthweights on his farm. This bull is no different than the other bulls I sell in that birthweight range, and if his EPD's have any accuracy, he will throw WAY lighter calves (likely in the 80 pound range). He is built right, a small head and closed in his shoulders. That means more than a birthweight!
On a side note; if you STRICTLY pick you bull based on birthweight, how do you factor in for a bull born as a result of an embryo implantation? If I put an embryo in a dexter, it will likely be MUCH SMALLER than if I put that same embryo in a big brahma cow! Same genetics, different birth weight. Birthweight is more a matter of ENVIRONMENT. But that is for another thread, another day.