I didn't read your exact article; I'd read earlier versions wherein it was stated that Woods reported it to the FBI. Thus, the FBI being in his driveway after 9-11.
Prior to 9-11, in August 2001, Woods became suspicious of the ME men, he reported it to the pilot and flight attendant, describing specifically what made him suspicious. They, in turn, reported it to the FAA. There is no public info, at least Woods didn't mention anything about what happened to the info after that, whether the FAA ignored it, or passed it on to the FBI, who didn't take it seriously.
After 9-11, a friend of Wood's encouraged him to report to the FBI the incident, and he did. This time, the FBI did take it seriously, recognized that his report was about the genuine hijackers.
From the interview, it was clear to me that Woods is not given to paranoia and hysteria, that he observed some specific behavior, which made him very suspicious. After 9-11, when he talked with the FBI, they told him, not to repeat publicly the specific behavior he observed, probably so as not to alert any potential terrorists, as to which specific behavior they need to change.