Well, I prefer to go with a simpler answer. I'm not going to try to develop some sort of psychological profile of Noel. Not going to make any assumptions about any emotional bias he might have about players of certain ages or whatnot. Rather than make a dramatic, sweeping, generalization of his character, I'll go with the simplest answer:
He benches guys who are playing like dumbasses. Just like any other coach. That's the simplest answer. It's not because he has something against young guys. It's just coincidence that these dumbasses also happened to be the young guys.
And it's not even if you aren't producing; it seems that it's fine if you aren't producing, as long as you are trying to play within the system (Jokinen). But if you're going to be unruly, unrepentant, or a dumbass, you're going to get a yelling at and riding the pine. As long as the effort is perceived, you're fine. As long as you make adjustments (Kane, Bogo) you're fine.
I really don't think it's fair to make this character assumption of him based on interactions with two players, when he's had successful interactions with others of a similar age. But now it seems it has 'stuck' with this community, and it's now 'fact' that Noel has an issue with young players. Fact.
On the Redmond thing...Claude Noel is in his late 50's. Everyone seems young to him. I'm in my 40's, and a 23 year old is not really different from a 21 year old to me. I would think Noel would feel similarly.