Well, JMHO, but you can't be forced to sign freight onto a manifest and then put another employees name on it. If your supervisor is telling you to do that, refuse to do it or go XGO. Under these circumstances someone higher up would certainly bring attention to it and the supervisors would eventually be discplined and fired for this.
I doubt they had a gun held to their head. It seems they had been in trouble for misloading several times and were trying to avoid those issues so were signing other employees names to the freight instead of their own.
As for an employee stealing. Whether it's a $1bottle of pop or a radio box. It is wrong and that employee must not have valued their job nor theirself to much to be doing something like that.
Now, when it comes to speeding, we all know that is chance you take. Every driver in the company has speeded while driving their truck. But you know they can check the computers in them see if you have been. So don't cry wolf when you get caught.
As for what happened Mr. J. G. it is very sad and that csm should be ashamed of himself for what he did to him.