I think he should still knock out a quick PhD in physics or similar, especially from a top notch school. There's got to be -something- he can learn being around and cooperating with really smart people. Or as his mom says, "You've got to have something to fall back on..."
Even if he gets accepted directly into a graduate program (I think this is very rare but he may qualify), the first couple years are not going to be dedicated to research. I agree that there would be a lot of value there for someone so young - what's the rush? - but I've never heard of a quick PhD.
1929–1941: Fellowship at Cambridge
PhD and fellowship
At the urging of Ramsey and others, Wittgenstein returned to Cambridge in 1929. Keynes wrote in a letter to his wife: "Well, God has arrived. I met him on the 5.15 train." Despite this fame, he could not initially work at Cambridge as he did not have a degree, so he applied as an advanced undergraduate. Russell noted that his previous residency was sufficient for a PhD, and urged him to offer the Tractatus as his thesis. It was examined in 1929 by Russell and Moore; at the end of the thesis defence, Wittgenstein clapped the two examiners on the shoulder and said, "Don't worry, I know you'll never understand it." Moore wrote in the examiner's report: "I myself consider that this is a work of genius; but, even if I am completely mistaken and it is nothing of the sort, it is well above the standard required for the Ph.D. degree."