No, in this case, it definitely would not be worse. The assumption was that Young is out. Iowa used a backup 149 at 157 this past weekend, so even if Murin is an underdog vs Berge, he clearly has a much better chance than his backup. The only weight where IA is worse is 141, and Desanto is the sacrificial lamb in such a move. There is absolutely nothing I've seen from Spencer Lee in the last two years to indicate that he wouldn't tear through anyone at either 125 or 133. If you make Lee wrestle 125, then the lineup goes:
125 Lee +6
133 Desanto -3
141 Eierman Even
149 Murin +4
157 Backup -4
Iowa has a +3 expected advantage in the first 5 classes. If you forfeit 125 to their backup, the it changes to this:
125 Forfeit +6
133 Lee +4
141 Desanto -5
149 Eierman +5
157 Murin -3
The +3 advantage is now +7. Even if you don't think Lee can major RBY, it's still +6. The advantage comes from giving away 6 to a backup instead of making a backup wrestle 157, who would almost assuredly lose badly. If they bump Lee and make their backup wrestle Howard in the same scenario, the +6 at 125 becomes -3 and it's now a clear disadvantage.
It's all a moot point now anyway.