HI- I am Matthews Uncle and would like to help address some of your questions to help clear thing up. Feel free to ask me anything, your help is appreciated.
First- The Valley at the trail referred to in the news article is a snapchat picture of the valley / mountains that was taken from Stunt & Saddle Peak rd., near the entrance of the trail that leads back to Rosas Overlook. Basically the parking lot at the intersection looking out toward the mountains / valley toward the north.
Matthew did frequent that area, but not to hike. He is not a hiker and had never spoke of hiking any trails.
Since the circumstances of his disappearance are so odd, the family has suspicions of foul play. Some of the people he was recently associating with have helped foster that belief.
Law enforcement is still handling this as a MP case.
It is way out of character for Matthew to just disappear. This is also the primary reason we tried focusing search efforts at the hillside , roads, and trails around where the car was found. Basically rule out the possibility he's out in the bush somewhere and move to the next theory- which includes foul play and different search parameters.
The information we have received from the police has changed over time, the case originally being handled by CHP and LA COunty Sheriff. Now turned over to LAPD M.P. division. Our last communication with them indicated they found the car unlocked with the trunk open, no signs of forced entry or vandalism. The x's on the car were put there by the SAR team to indicate the vehicle was searched.