I have a two year old rooster and a one year old rooster, both in completely different pens, who have never crowed. They're the sweetest chickens I own. The one is an omega in the pecking order, but the other is housed alone with a single hen and has never tried to mount her. I'm thinking he may fancy other roosters over hens
One thing I worry in your situation is he will feel the need to become the alpha and start crowing for you. Especially if his current owners have other roosters. If he suddenly is the only man of the flock, he may go nuts and you'll have to give him up. I really cannot say, roosters are very puzzling sometimes.