I see many have jumped on this story prematurely as a way to attack the administration and their common sense muslim policy.

However there are some very key words in the article worth mentioning

1) He cancelled his own trip. It doesn't appear that anyone in the government cancelled it or said he couldn't travel
2) It was unclear which authorities communicated with Khan or what privileges were under review. Yolanda Choates, a spokesperson for U.S. Customs and Border Protection, declined to comment about Khan specifically. (directly from the article)

So while there are many whose hair is on fire over this story, there is much that is missing before any rational person can yield a judgement. But, that apparently doesn't stop many of our friends on the left. Never fear for I am here to bring logic and common sense to an otherwise troubled board