He's trying to break into acting but does paid audience work until that opportunity arises. ... By no means has he reached his career goals, it's a supplement.
Everything in business is about networking. By showing up to multiple productions, he's visible to some production people. By coming back and sitting through long taping sessions, he is showing his reliability. While he's likely visible only to the low-level production types, people move up the ladder or jump to different ladders. Can't hurt.
Frankly, it's no different than being an extra on a movie or television set. No one answers "what do you do?" with "I'm a professional extra." It's just another way for L.A.'s large pool of waiter-actors to avoid having to take the midnight train to Georgia (or the midnight plane to Houston, as I learned watching
$25,000 Pyramid).