Is it fair to say that neo-racism is the opposite of nationaism?
No.
Nationalism regards the citizens of a country having a mutual (national) identity, and respected for acting (morally) in the interest thereof.
Neo-racism regards those who ostensibly pursued MLK’s “dream”, only to abandon it when they realized achieving it didn’t automatically redistribute wealth from their betters - so they returned to race-centric tribalism to destroy their way to prosperity (which won’t work either).