There are hundreds of Don Nelson's at NASA. Anyone with any knowledge at NASA knows that accidents will happen in an R&D program. We've lost many good men in X-planes, trying to improve the aircraft potential.
The only reason Don Nelson has come to light is because of his web site, IMO. John Young, the STS-1 Commander, is still shouting that we should NEVER land at KSC. He wants ALL landings at Edwards AFB. Obviously, Edwards is safer but the only SAFE way to fly is to NOT FLY.
Also, if NASA had implemented all the illogical/cost ineffective fixes/changes proposed by Don Nelson, it would not have changed one iota regarding this particular issue. Seems that any time one is close to making sausage, it's easy to see the flaws.
Hugs, Gracey