I'm too young to remember the Challenger personally but here are two theories when it comes to making documentaries: 1) his public appearance made him seem important at the time, but he was essentially a mouthpiece for others who were more entrenched in the story and 2) the creators could be either too old or too young, either assuming everyone would already know him or that he was some irrelevant character since he never came up during interviews. Either way, sounds like he could have been cut for time. Especially if his role was mainly media based since media offer us a window to the drama and the documentarian was already backstage in the thick of it.