For the most part you don't really need to understand linear algebra for most things -- engineers past have done a great job on abstracting interesting math problems away in everything.

If you're not constantly working with linear algebra, you're going to get rusty fast. Mind you, he seems like he writes a matrix multiplication with goto based loops every time, so he can make sure that he keeps knowing linear algebra, and to prevent the business he's working at from getting anything done because he doesn't like their ethics