Well, he clearly failed basic geometry and navigation. Would you call 2 degrees at 12 miles adequate separation? I don't call an RA a vanishingly small risk of collision.
He did just sit there and nearly have a collision - he was amazed when the 737 appeared to move laterally in front of him. What makes you think he could have manoeuvred enough when he realised it was seriously going to poo? Having something in sight doesn't mean you won't be hit by it.
You know very well that eyewitness statements are some of the least reliable evidence available. People are very poor observers. Being a business man changes this not one tiny bit
You've clearly never worked in ATC - the only constant is change.