I hate to jump into this topic and I'll try not to take sides but...

There is actually pretty strong evidence that is actually was to put people of color in jail (at least initially).

At the very least enough plausible evidence to show that throwing around "bs" like that might be misguided.

https://harpers.org/archive/2016/04/legalize-it-all/

> "The Nixon campaign in 1968, and the Nixon White House after that, had two enemies: the antiwar left and black people. You understand what I’m saying? We knew we couldn’t make it illegal to be either against the war or black, but by getting the public to associate the hippies with marijuana and blacks with heroin, and then criminalizing both heavily, we could disrupt those communities. We could arrest their leaders, raid their homes, break up their meetings, and vilify them night after night on the evening news. Did we know we were lying about the drugs? Of course we did.”

"The Nixon campaign in 1968, and the Nixon White House after that, had two enemies: the antiwar left and black people. You understand what I’m saying? We knew we couldn’t make it illegal to be either against the war or black, but by getting the public to associate the hippies with marijuana and blacks with heroin, and then criminalizing both heavily, we could disrupt those communities. We could arrest their leaders, raid their homes, break up their meetings, and vilify them night after night on the evening news. Did we know we were lying about the drugs? Of course we did."

- John Ehrlichman

Source: https://harpers.org/archive/2016/04/legalize-it-all/

Adam Ruins Everything - The Sinister Reason Weed is Illegal

https://www.youtube.com/watch?v=CJlqsdezhhk