By what book exactly? The Nation of Islam isn't even technically muslim.
George Lincoln Rockwell represented a bunch of people too, but I'd judge pretty harshly anybody who met with him. I think it's more than a little odd how many politicians have met with Farrakhan.
There's nothing odd about it. Minus the anti-Semitism, homophobia, and the crookedness of Farrakhan he talks about the same things as Malcolm X, and that ideology grew quite popular as the 60s wore on. Black people like the avowed message of self-reliance, self-determination, and local ownership that the Nation of Islam talks about. The NOI wants an independent African American community, and in their mind that means racial separation. Many black folks subscribe to this idea that integration has done little for us. Black politicians – the people you refer to when you say the many politicians that have met with Farrakhan – have to meet with Farrakhan and his ilk in order to prove to black people that they stand for community-based action, not top-down action. Contrary to popular belief and the types of polls done with black people, black people today are likely more conservative than the general population thinks. Again, black politicians have to prove their in line with that thinking.
This isn't someone making an off-color joke at a social function; this is someone with a lifetime's worth of anti-Jewish sentiment. If a photo surfaced of Ted Cruz meeting with Richard Spencer surfaced, he'd be out of office before the end of the week-and rightly so-even if they only talked about unemployment or the opioid crisis.
Ted Cruz is an ally of Steve King. There are a lot of Steve Kings in the House of Representatives. Here's the difference between politicians that have appeared with Farrakhan and those politicians that have appeared with Steve King: not nary a member of the Congressional Black Caucus has called for the destruction of Israel or proposed policies that hurt Israel, but members of the Freedom Caucus quite frequently denigrate poor black women, men, and children. Chris McDaniel, the guy running for Mississippi's open Senate seat, said that rap music had no redeemable value, and was more destructive to the black community than it has been positive. What we know is that politicians like King are more willing to act on policies that harm minorities – especially blacks – than people like Keith Ellison, Andre Carson, or Maxine Waters.