I also agree, with any of the genetic diseases. There are plenty of good horses out there without furthering a disease for the sake of the all mighty dollar.
I have Poco Bueno bred horses myself, my grandfather started the farm with a son of Poco Dell over 50 years ago. I've had all of mine tested and they are all negative, had they been carriers, there's not a chance I'd consider using them for breeding stock. It's just irresponsible.
I've seen firsthand what herda can do to a horse and it's gruesome. I don't understand wanting to take that chance.
Life is like a camera. Focus on what's important, Capture the good times, Develop from the negatives and if things don't work out, Take another shot.