I don't think that's impressive. You know what's impressive? A doctor who invents penicillin and saves millions of lives. An inventor who creates a printing press that allows information to be distributed to the entire world. Now that's systemic, broad change.
The KKK is an irrelevant, dying organisation with a few hundred members in a country of 320 million people. Convincing a couple of members to quit the organisation (and probably remain racists in their daily life anyway) isn't impressive. It's actually, if anything, an incredibly inefficient use of time. A video on youtube can reach potentially millions of people. Yet this guy wastes time speaking to people one-on-one.
An average cop probably does more in one week to enact change in his community than this guy ever did in his life. It's just a feel good story. Mysteriously works great on most people even though the scale and impact is meaningless.
It's like when people are proud to themselves because they used a reusable bag at the supermarket. Meanwhile, some of us are petitioning the government to regulate plastic and enact broad, sweeping changes in society. A completely different scale...