I've worked with at least 3 older IC software engineers (close to retirement age) and their experience has been invaluable in forseeing issues that younger people don't spot in advance due to limited experience. Also the breadth of the work that these people have been involved in is very useful in being able to pull experience from other areas into an unrelated project. I genuinely don't understand the bias against this unless the person is unwilling to learn new things which hasn't been my experience.

Hopefully this attitude will change as the valley ages and people will learn that a lot of software engineering principles don't change as quickly as the buzzwords do.