In a country of over 300 million it is not at all difficult to believe that some moslems celebrated as the towers went down. But I’ve seen no evidence that crowds of “thousands and thousands” celebrated together in the streets if Jersey City on Sept. 11. The WaPo reports “a number,” celebrated, but that is a very indeterminate description, and context suggests a few or perhaps even a dozen or several score.
It may be that trump is confusing what he saw in Jersey City with want he well may have s÷n on TV: throngs, thousands and thousands of cheering moslem polypstinians in the Arab-occupied West Bank.
Or, perhaps, he saw a few in Jersey City, and his mind inflated that to “thousands and thoussnds.” He is a man who seems to exaggerate things, so that seems most likely.
Depending on how many Muslims live in that terrorist "incubator" of Jersey City (see my post above), there could easily have been hundreds or more cheering, if not publicly, but privately among themselves.