Richard, if you want to be pedantic - and channel Paris Dennard - then yes it's true that Obama did not specifically condemn Roof or white supremacists. However the reality is that Roof was arrested shortly before Obama's initial speech and therefore he could not comment on the ongoing investigation. Obama did clearly talk about the racially based motivation for the attack. Roof's involvement with white supremacy was not clear at the time although the racial motivation itself was clear.

Compare that to what happened in Charlottesville where obvious, even self described, white supremacists gathered and it doesn't take a genius to figure out what was going on. Yet instead Trump equivocates in his initial response, equates the anti-fascist protestors with the Neo-Nazis (and conveniently forgets that he did so when he referred to it in Phoenix). It then takes hm 2 days to clarify his position and condemn the white supremacists.

I don't see a double standard, I see a lack of leadership.