Good on the OP not wanting to bash anybody. That leaves it up to me then!
How do I quantify that Roush's work is defective? Simple, the rocker arm shaft nut backed off, which resulted in a broken shaft. Now either the owner loosened it up or we believe him when he says he's never opened the motor. There is no history, that I know off, where FE rocker shaft nuts/bolts back off on their own WITHIN 2,000 miles of being installed. It just doesn't happen, that nut was not tight from the factory is the only reasonable explanation. PLUS, it was noted several other nuts/bolts were loose as well. This is very strong evidence of defective workmanship.
I'm sure open to other plausible reasons for such an occurance. I totally understand now wanting to bash anybody, dealers do take a beating, often undeserved. That does not appear to be the case here, from what we have heard (without cross examination) Roush is looking very guilty on this one. Not a bash, just the facts.
HTOB's are to risky for my taste, I don't care who makes it or put's it in, when it fails (and all to often they do) it's a nightmare of a repair job. Don't need the risk or the hassle.