On a 1,000 lb holstein 60+ days of feeding corn would be well worth it in added yield vs just 30 days and then butcher.
I'd feed the corn hard and just enough hay [3-4 lbs a day] for the scratch factor to keep his stomach moving.
Holsteins will often stall out at 1,000 - 1,100 lbs without a protein pellet added to the grain mix.
I've never butchered a silage fed steer early, so I couldn't even say for sure how strong the taste may be.
I'm sure 30 days on corn and hay would help some and better than just another 30 days on his current ration
It's darn hard to get a holstein steer to finish on just corn silage and hay or grass.