I have a family member who owns such a company. Not the one profiled. In fact, he's never been interviewed. He always declines when asked.
There has been a distinct grey area concerning this task. Police, rescue workers, crime scene techs, etc...are not allowed nor legally obligated to do any kind of clean up or restoration. For a long time, that has fallen on the family members. It is a horrible thing for someone to deal with. As much as it makes us want to throw up (and yes, I have a REALLY hard time with it) imagine what the victim's family feels when they walk back into their property to see what's left behind. It's traumatic to say the least.
I've seen the commericals for that series. I have to admit, I'm kind of glad we don't get Nat Geo LOL!