If Buchanan had been elected in 2000 I doubt he could have done much to stop Atta and 9-11. I also don’t blame Bush, even though he was absolutely horrible on immigration through and through, from supporting amnesty and increases in legal immigration to helping popularize new nauseating platitudes like ‘family values don’t stop at the Rio Grande’ or ‘Islam is a religion of peace’.
But had Buchanan been elected in 92 or 96 and had he been able to put in place his preferred restrictive immigration policies then who knows? Maybe garbage like Atta wouldn’t have been allowed in.
I admit it’s speculative, but that’s all we can do is speculate about what might have beers. One thing we don’t really need to speculate about though is that current immigration/refugee/asylum policy predictably continued to import terrorists even after 9-11.
As to Buchanan and Afghanistan; I think he would have gone there. Even if he didn’t want to, public pressure would have demanded it. He probably wouldn’t have gone to Iraq, and in that he would have been right.