When faced with a difficult decision that will negatively impact other employees, you try to...
Just state the facts--that should speak for itself.
Try and provide evidence to prove this choice is best.
Explain that you don't want to do this, but you have to.
Offer to provide whatever help you can as they go through this change.
Make it clear this is best for the company and will help them in the long term.
Keep it short and non-confrontational.