However, rather than re-hash all that, it's worth taking a look at the numbers - numbers that absolutely indicate a younger skewing workforce. For instance, the average age at Facebook is 26, and 31 at Google. Tech as a whole leans young, with the "oldest" tech company workforce (HP) still younger than the national median [1]
Now, whether simply having a younger workforce points towards actual age discrimination is a matter of fair debate. A perfectly reasonable explanation might be that tech is a young field, hence a young workforce. However, there are enough confounding factors (limitations of experience, work/life balance in dev roles, etc.) that certainly make for rational arguments in favor of age being more of burden than boon.
Then, of course, you have stuff like this :
> "Young people are just smarter. Why are most chess masters under 30? I don't know. Young people just have simpler lives. We may not own a car. We may not have family. Simplicity in life allows you to focus on what's important." -- Zuckerberg
True or not, it would be weird to argue that his opinion is somehow a rare isolated outlier. It speaks to a common conception - both in the valley and in tech - that this is a business for the young.
[1] http://bits.blogs.nytimes.com/2013/07/05/technology-workers-...
In others, especially those with the high-strung startup mentality you mention, they are looking for people to work more hours for less pay and promises. Younger people are more able / willing to take risks. Experienced workers are not as interested in promises, but prefer defined returns on their individual investments.
Since he was explicitly told that they wouldn't be sending his resume to anyone else that pretty much means the failings are purely resume-based, not ability or interview skills. I have a hard time picturing a resume making one unemployable other than due to age discrimination.
