The best argument anyone has made for Trump’s time machine journey against who? George W. Bush? The Saudis?
But it still doesn’t justify this off the rails behavior.
The Iraq war probably played the biggest role in the GOP demise in 2006 and 2008. I see Trump continuing this 9/11 gambit as an effort to try and swing those lost presidential voters back to the GOP. Also realize that his comment about 9/11 happening on Bush's watch was in response to Jeb saying W. kept the country safe - it did not come out of the blue.
Trump IMO on this point is looking past the primaries to the general.