It's an indirect defense, but "they're bad too" is a defense. Insisting on juxtaposing Nazi's with Left Wing terrorists effectively diminishes the critique of the right-wing terror...I assume you will disagree, but I bet if you were to change out the groups in question, you would see what I'm talking about.
Further, Alt-right didn't "pop-up" Trump invited them into the process the day he hired Steve Bannon. Why do you think Bannon was hired? You really think Trump's walk-back was about espousing truth? I think it was about maintaining a well organized and motivated voting block.