A "lurker" familiar with the history of US-resident Muslims fighting against the Soviet-backed Afghan state has responded:
This is mostly true. There were actually many folks in the U.S. that went to Afghanistan during the 1980's to fight against the Soviets. In 'Looming Tower' by Lawrence Wright, he discusses in the first 100 pages or so how a guy in Kansas City, MO was recruited via a flyer and called a number in Peshawar which got him into the Muj pipeline.

Where the quote isn't entirely correct is the notion that all of these Americans fell into Bin Laden or Zawahiri's hands. There were many Americans that went through but then one wasn't there the entire time nor were all Americans processed through him. The same is for Zawahiri. There were many guest house in Pakistan and there's no way that all the Americans were in the grasp of bin Laden.

Azzam Had set up many guest houses and they were not all controlled by Bin Laden. I'm not aware of any of these stories about lost passports. The bottom line is that not everyone that went to Afghanistan to fight against the Soviets became a member of Al Qaeda'.
If that was the American experience when fighting a Soviet-backed regime was approved of by the US government and many others across the political spectrum, it is clear that very few if any of those who returned continued to wage the violent jihad in the USA. Certainly puts the hype and fear over a possible current threat in a very different perspective.