That is a terrible idea for a beef steer. To gain 4-5lbs a day he's gonna have to eat around 30lbs/day of grain. Without the hay to keep the rumen under control, he will bloat up like a balloon and die. Hay should be offered free choice, as much as the steer will eat. Sometimes you can get by without feeding a dairy steer hay, but they have been bred to handle extremely high energy diets whereas beef cattle have been bred to handle mostly forage-based diets.
Beef vs dairy type is inconsequential; any cow can be transitioned to a high grain diet. Is risk of bloat increased? Of course it is, but it is in dairy animals, too. Is bloat inevitable if the steer is managed well? No. The exact name provided doesn't correspond to any Purina feed I'm aware of but my educated guess is that by "performance" she means one of the show feeds, all of which are complete feeds containing adequate roughage to stimulate the rumen. If they're really worried about it they can top dress with sodium bicarbonate. There are thousands of head of beef cattle in show barns all over the country right now who don't eat a speck of hay, better get to running around and reminding them they're supposed to be bloated.
The poster needs 4-5 lbs ADG. The hay is interfering with that, ain't no ifs ands and buts about it. Risks will always be increased when you push a cow to the extremes of performance. Either they accept the risk and do what needs to be done to meet the goal, or they keep feeding hay and the steer probably doesn't make weight. Yes, ideally growth would never need to be pushed to this point and hay could be offered free choice and we could all stand around singing kumbaya, but such is the predicament.
There is no silver bullet to quickly put on the weight. Start with genetics that will allow good growth, keep the calf parasite free, increase the TDN of the ration, increase the amount of the ration consumed, don't let the animal burn it all off and consider an implant if it's "legal" at your show.
If you're really interested there is no shortage of literature on feeding beef cattle high grain diets. Google is your friend. :tiphat: