I'm tempted to say that RP is being loyal to a fault, but I suspect it is more than customary loyalty. This degree of protection is usually reserved for one's friends or family members. I believe his explanation, but do not accept his obligation to cover for anyone, unless that person is very close to him.
Example: the other day I took my 8 year old son to a Chinese restaurant. In the presence of the waiter, my son asked if their was dog on the menu. I was very embarassed, and probably would have made less of an issue about it (considering his age), if he hadn't repeated it, with a devilish grin on his little face. I was very upset. However, at his age, I am very responsible for everything he sees, hears, and repeats.
I know that's an extreme example, but I can envision a close friend or family member, someone younger, less wise, and trusted doing something as embarassing as this, essentially betraying a trust, but being forgiven, enlightened, and restored. If this was a young family member or a friend to whom he's remained close, his protection would make sense. Ragardless of who the writer was, though, he needs to step up, man up, and come clean. It's too important, and it's that time.
I don't know who this was. Some have said Rockwell. That's what Dondero says, but Dondero says lots of things. Whoever it was needs to come forward. Now.