Why Kim Jong eun was not invited to visit the US

At a breakfast meeting at the Ford Foundation, sponsored by Syracuse's Maxwell School and Public Agenda, ambassador Donald Gregg was interviewed by NPR's Robert Siegel.
Gregg's long service as a CIA agent, national security advisor, ambassador to South Korea, and president of the New York Korea Society has sharpened his eye towards advancing static US foreign policy. During his interview with Siegel, the phrase of 'speaking truth to power' became a recurring theme. Others call it 'profiles in courage'.
Whilst CIA station chief after his bosses in Washington told him to let sleeping dogs lie in response to a cable alerting them of a tortured Korean American professors' torture and suicide at the hands of the notorious KCIA during the Park Chung Hee dictatorship.
Ignoring Washington's advice, Gregg confronted the ministry of Justice. On his own, he managed to tone down the KCIA's torture protesting the Yushin constitution and the Park dictatorship, resulting in the replacement of a KCIA senior official who condoned extreme measures.
The former ambassador is not without a degree of courage. A nimble mind, a sharp eye to detect openings for the US striking an advantage to calm tensions and shunt to diplomatic change, he has encouraged dialogue with the DPRK, especially at a time of US and South Korean coordinated policy that calls for 'roll back'.
Call Gregg's approach 'Track II', he has managed to facilitate an exchange between Syracuse's Maxwell School and a North Korean technology university, now in its 10 year.
Never one to miss an opportunity, Gregg at the time when the name of Kim Jong eun began to emerge as his father's successor, boldly and commonsensically suggested to the White House, for an invitation to Kim Jong eun to visit the US. In this way, the US government could get a measure of the young man, and in turn, he could know the Americans, the more especially since he was educated in a Swiss gynasium or lycee, and may even speak reasonable English. And since his name was being floated in the media and blogosphere, the opportunity to get to know him, and here was the right moment to ask him to vist the US>
Gregg never stops saying that North Korea is America's greatest intelligence failure. And there is more than a grain of truth in what he is saying. His suggestion was shot down. The Obama administration wasn't amused!, it seems.
On the other hand, North Korea might have turned an invitation down. Or might not.
The mere fact of extending such an invitation would signal to Kim Jong il & co., the US was willing to reopen dialogue with the North.
We shall never know, the more especially when an occasion arises for a breakthrough, you can count on Obama to let it slide by, and it is becoming more and more noticeable that that will be a judgment written on the tombstone of his years at the White House.
On the other hand, Gregg continues on his lonely road, clear of eye, sharp of mind, speaking truth to power and looking to open shut minds in Washington.