3: In August of [1998], the intelligence community had received information that a group of Libyans hoped to crash a plane into the World Trade Center. (344-345). The Commission does not explicitly say that the plane would be hijacked from within the United States, but it also does not explicitly say otherwise.
Page 264-265
The 9/11 Commission Report: Omissions and Distortions
David Ray Griffin

This isn’t exactly a complete view of the claim. The full sentence in the report, for instance, simply says:

In August of the same year, the intelligence community had received information that a group of Libyans hoped to crash a plane into the World Trade Center.

No mention of hijacking here. Footnote from the 9/11 Commission report tells us more:

For the August report, see Intelligence report,"Terrorism: Alleged Threat by Arab Terrorists to Attack the World Trade Center in New York," Aug. 12, 1998. An FAA civil aviation security official believed the plan was improbable because Libyan planes were required to operate within airspace limitations and the Libyans did not possess aircraft with the necessary range to make good on the threat. Jack S. interview (June 13, 2004). On September 30, 1999, the FAA closed the file on the August report after investigation could not corroborate the report, and the source's credibility was deemed suspect. FAA report,Transportation Security Intelligence ICF Report 980162, undated; but see FAA/TSA rebuttal to the Joint Inquiry's Sept. 18, 2002, staff statement, undated, p. 1 (stating that the FAA did not formally analyze this threat).
Footnote #14 to Chapter 1
9/11 Commission Report

Dr Griffin ignores the finding that this claim could not be corroborated, and the source wasn’t deemed to be credible. 

His statement that the Commission does not “explicitly” say that the “plane would be hijacked from within the United States” is correct, but misleading. The comment that “the Libyans did not possess aircraft with the necessary range to make good on the threat” plainly indicates that they were expecting the attack to come from overseas.

This example fails Dr Griffin’s test, then, as it isn’t about “the threat of terrorists hijacking commercial airliners within the United States”. It does contain the threat of using planes as weapons, but this is lessened by the fact that it could not be corroborated. And if the source wasn’t deemed credible then it’s hard to see why NORAD (or anyone else) should have taken this particularly seriously.