I know a thing or two about the SKS.
To boil it all down, yes the safety is perfectly reliable.
While true in a perfect world, the SKS was built in factories that were driven to produce large numbers. There is a common issue with sear engagement on the SKS.
Before you go trusting that safety during an accidental drop, google "SKS sear engagement test" and read. It should be an eye opener.
I don't have mine any more, but I did the check and found out I had negative sear engagement. There was a good chance it would fire if dropped.
I found Kivaari's Triggers online and for $60 with a one week turn around he fixed my sear engagement and reduced trigger travel and the pull to 4lbs. You ship the trigger group to him, not the rifle.