I see you are learning to wait for your 4 AM talking points instead of just waking up, triggered, and going off on your own little rants.
So you've noticed that people, when they get frustrated and try to construct insults, tend to reveal things about their back-ground, upbringing, prejudices.
For example, someone might say, "I have more respect for street dogs than i have respect for you".
In this case, the top definition at the Urban Dictionary says this phrase is now used more as a replacement for other, more offensive terms, used for emphasis, such as the F-bomb and GD.
"TOP DEFINITION
Cotton Pickin
Something people say when they
get mad.
Or it is a replacement for
GD or
Gosh Darn it."
In recent memory, it was popularized by Bugs Bunny to lend emphasis to just about any expression of astonishment.
Disconnected from it's original, supremacistic roots (against either a race, or an underclass), it could be used by someone
who does not see color.
Which is why it is possible to not know what he meant.
People use slang all the time that they have never really researched.
He could have meant the most popular usage, per the Urban Dictionary.