At Kris Black's female sale last year, there were several heifers sired by Gringo for sale along with a couple of 3 yr old cows with very good calves sired by Gringo. He did not have any of the shorthorn heifers bred to Gringo. That's all I know about him. I think he is a very good bull (deceased I believe), but not sure about using him on heifers.
See post on buyers remorse on the other site. It's painfully frustrating sometimes what happens to your cattle after you sell them. I'd just recommend to them that they call the bull owner and ask about use on heifers. He might be ok, but I'm guessing not based on what I've seen. They must be hoping to raise that great shorthorn steer, but aren't patient enough to give it a year. You might get away using him on an older heifer, but using him on a heifer that is fed for show may be asking for trouble.