1. Speed and space can be difficult to predict without considerable experience.
2. The libraries are not as extensive and tested compared to conventional choices such as Java or C++.
The books you have are just fine. The books were high quality when they first came out. Thousands of us studied the first printings without ill effects. Besides, you have the opportunity to test your reading by looking for errors. Just relax and enjoy a masterpiece.
At age 58, his life expectancy is around 20 years, and he could live 10 years or more beyond that, probably with rising care costs throughout. Once he leaves the workforce, voluntarily or involuntarily, he will be completely dependent on savings, retirement plans, and Social Security to support himself and any dependents. Staying in the workforce delays drawing down his savings, reducing the risk of running out of money at the far end---when he can't do a d-d thing about it. So, yeah, it makes sense that he wants to keep working, independent of whether he "should" be able to stretch his money.