It seems to me that that's the mentality of a narcissist, that even after all those examples, and Clinton's retaliation with missile strikes in Sudan and Afghanistan, that he still concluded that the US was a "paper tiger." At least the Japanese Empire learned their mistake after Pearl Harbor; unfortunate that UBL didn't have the capacity to learn from that as well.
So concluding that 9/11 is the result of Black Hawk Down is only true in an indirect, historic, hindsights' 20-20 sense or POV of UBL sense. Unfortunately that's not a very informative conclusion to make for looking at new situations, as it hinges on the irrational and unpredictable nature of a guy like UBL who's too stupid yet personally ambitious to realize his plans were not working (not getting the US out of the Middle East). It's like the people that say appeasement doesn't work because Chamberlain and Hitler blah blah blah; well, Hitler was a unique character and the circumstances were specific to the point that you could not recreate those conditions again. Bringing it back around, it certainly offers no concrete guidance for our current situation in Syria. We cannot say that not striking=another 9/11, or striking=another 9/11 with any degree of certainty.