"Mr. Mukerjee contends he asked to leave the screening area and return to the pre-security section of the terminal, with the intention of simply stepping back in line and going through screening again, but was not allowed. This is absolutely correct, at this time he was in limbo, he was not being detained, but he could not leave. A person cannot simply leave the security area of any airport once they are on the airside but have not satisfactorily completed screening. Once a person has passed through security, but is not cleared to fly and then chooses to leave, such as Mr. Mukerjee, s/he must be escorted out of the secure area (and usually the terminal)."
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Deciding if I am detained: a rule of thumb.
If I receive word about an urgent emergency, such as my wife being hit by a bus or about to give birth, can I immediately go to the hospital? If yes, I am free. If not, I am detained.
This rule breaks down a bit on amusement park rides, but one would assume the ride operators would immediately let you off if you could communicate with them and, in any case, you're only going to be stuck there for a couple of minutes at the most.
Mukerjee was not in "limbo". He was detained. When someone chooses to redefine words White-House-style I tend to view whatever else they say as though they are serving an agenda.