Your analysis is accurate, as far as it goes.

However, several things to consider:

1. The actuarial factor applies from the point at which you stop growing your portfolio and start drawing it down. Thus, comparing a 45-year-old working man and a 67-year-old about to retire is an apples-to-oranges comparison.

2. A critical difference is if you're trying to amass a large enough portfolio that will (almost) guarantee leaving a large bequest to your kids. In that scenario, the rule-of-25 (or rule-of-33 if you assume that real returns in the coming decades will be closer to 3% than 4%) would be the appropriate starting point.

3. Finally, if you use the value determined by the life expectancy of a person your gender and age, you're targeting the mid-point of probability, since life expectancy is the length of time over which 50% of people will die (assuming they start at your age and are of your gender). I don't know about you, but I certainly would prefer a much lower than 50% probability of running out of money before I die.