No one cares about David Duke. He can't even get elected dogcatcher, but he'll happily run. He's been a felon has-been for as long as I can remember. Why do you encourage him?
Why is someone like Duke attracted to Trump? Think about it...
There is no rational explanation for crazy on either end of the spectrum. For every nutjob rightie, there's a nutjob leftie. If they are lone whackos, with very limited if any support, they are just delusional, so insignificant IMO.
No way a David Duke endorsement carries any weight ... it is like a Joan Baez endorsement ... totally obvious and equally relevant.