Reality TV isn't. It never has been, it never will be, and we all know that. It has no connection to reality. Still, it's a huge global phenomenon, attracting viewers from all walks of life and every demographic imaginable.
Even if you yourself do not watch reality TV, your kids know about it and have probably seen some of it. More importantly, this genre has become a new "safe" conversation topic, akin to discussing the weather or the most recent football game. It is almost always reasonable to ask an acquaintance, "So, who do you think will win this round of American Idol/Survivor/America's Next Top Model?" or "What do you think of this season of American Chopper/Real Housewives/Wife Swap?" Such conversation is a way to break the ice for most American age groups today. However, the content of such shows is rarely kid friendly, and certainly not Aspie friendly. So how do you and your child navigate it?
If you do watch reality TV, you know that people often behave very poorly on these shows, especially the competitive ones. Point that behavior out to your child and discuss it. And, in general, discuss with your child that how people behave on television is not how they behave when the cameras are off. With the competitive shows, try to guide your child towards ones that promote positive behavior or skills. While people might not behave well on American Idol, at least it has the benefit of being a talent show. Ask your child whose performance he liked best and why. If he likes a particular song, find the original recording of that song and play it for him along with similar songs or works by the same artist. It can be a good starting point for expanding interest while taking part in something that is popular.
As for noncompetitive shows, I recommend previewing different shows on TLC and the Discovery Channel. These often take the form of "improvised" documentaries, where people who do something for a living or a hobby allow the cameras to follow them in their activities. While the behavior of those on camera can still be distasteful, that behavior is not used as a selling point of the show. And again, watching a reality show about a chef can be used to spark an interest in cooking, a show about mechanics can develop an interest in engineering of various kinds.
As always, I recommend previewing anything you might show your child and viewing via the Internet so as to avoid most of the advertising found on cable television.