When I think of Shorthorns: pretty cattle with large birth weights, slow to nurse, no vigor (large birth weights the cause) slow to finish and hard to sell commercially. This is the stigma that dogs the breed, not TH. Not that any of these are accurate but they are the things I've heard over the years.
I have seen some real easy doing Shorthorn calves but I have also seen some hard doing ones as well.
I think you need to work on changing those perceptions before you try and hang the breeds struggles on Genetic defects. You can easily select a bull that will insure you do not have TH, I bet there are more THF bulls out there then there are calving ease. Even if the bulls is caving ease you have the cows side to deal with. I have a 50 50 shot of getting a THF calf out of a THC and a THF mating, how long will it take to breed calf size out of one?
Hereford is getting in on marketing the breed as a better choice on the grill, has Shorthorn?
I actually like a lot of the Shorthorn cattle I've seen, I just think your trying to pick low growing fruit in your cause, that has a lesser impact on the breed than a lot of other things.