"So, when history whitewashes Martin Luther King Jr. and others as having not faced adversity in their striving for equality and the betterment of all people, it downplays their more radical ideations."

Not 100% sure who is 'their' in this statement. Also, I don't think history ever said that MLK did not face adversity [to better his people and most importantly all people's lives]. I wouldn't equate 'having radical ideations' with the notion that the radical ideations would necessarily lead to 'the betterment of all people'.

I think you want to say that because we view him favorably, therefore our exposure to his more radical ideations is very limited.

(Response contributed by Bhav Tripathi, CRO at VotingSmarter)