It's probably not really feasible (problems of definition) but I'd love to see some statistics on average age of unsuccessful startup founders, preferably correlated with industry sector, as they've done here, and perhaps with some context of previous / subsequent success by the individual.
As noted in TFA, it seems likely the IT industry would heavily skew the results.
I may be wrong, but I think the problem is that startups are by and large unsuccessful across the board. It's a bit like trying to find the cause of a disease by looking at what doesn't cause a disease.
I did a quick search and got a lot of different answers, but the overwhelming number I got was that "over 90%" of startups fail in the first 3 years. With that, the number of possible common variables is going to be overwhelming.
However, it does potentially answer the question of why successful founders tend to be in their 40's. If you have a 90% chance of failing in the first 3 years, if you start 10 startups, perhaps you have a good chance of succeeding ;-)
As noted in TFA, it seems likely the IT industry would heavily skew the results.