Yes, he should. It's very important to the overall fiction, and to MGSV (both GZ and Phantom Pain).
Really, the fact that this game has so much disdain, even from fans of the series bums me out. Yeah, it has problems, almost all of which because it was originally built as a PSP game. But he should play it. Hell, I'll go online and walk him through it in co-op if I have to!