Don't know what industry/company you in, I admit I am surprised that they would rule out experience (aka people > 40 yrs) over youth. It gives me the impression that the industry has low entry barrier, that means easy for people to enter.

I am a technical manager, managing 2 teams of engineers. In our industry continuous learning (on the job, structured professional courses and advanced academic degrees) is par for the course. You can imagine the length of time the staff would spend on honing his experience and skill sets. They get better as they handle more projects. So unless a young engineer display great leadership and technical skills, it is not logical to promote inexperienced staff over the highly trained and experienced ones.

Having said that, younger people have the advantage of higher energy levels and stamina. In our industry we do have youngish managers who are very driven - handling big projects and still attending night classes to upgrade their professional knowledge.