I'm also not surprised that investors are biased. As a group, they are just people with money. That feature doesn't preclude them from being unreasonable in the way (one would hope) being an engineer implies a certain level of objective rationality...
What does surprise me is the fear that is apparently spreading among aging engineers. You didn't get where you are by being afraid. Every problem you've ever solved proves your ability to bend systems to your will. You design your own fate. Don't make yourself vulnerable by believing anything else.
On a more practical note, if college students had more opportunity to team up with older professionals on small co-owned projects, I think that would go a long way toward bridging the gap. Exposure is key. That's like, behavior therapy 101.