I grew up near Mt Baldy (actually, the 'official' name is Mt San Antonio). There are areas of trail around Baldy that have steep drop offs with loose rocks and when snow gets on those trails the edges can be camouflaged and make things very dangerous.
The area isn't 'full of mountain lions', you'd be more likely to encounter a black bear than a mountain lion. Of course, an encounter with either should be avoided. Carry bear spray and make lots of noise. Unless you're between a mama and a baby or between a critter and a carcass they're more interested in avoiding you than you are in avoiding them.
I hope Mr Sands was prepared for the weather and knowledgeable about the area. The S & R teams in the area are top notch so I believe he'll be found.