I won't attempt to come up with a hypothetical equivalent, since ethnic slurs are really not my strong suit. But it's fair to assume that if Kirk had used any sort of pejorative racial term to refer to Rush, he would have soon been renouncing it in a desperate attempt to save his political career.
It's true that Kirk grew up in comfortable circumstances, attended outstanding institutions of higher education and lives in a serene suburb where African-Americans are thin on the ground. So calling him a highborn dilettante unversed in urban problems is not outrageous, though it is irrelevant.
After all, I would guess that on the West Side of Chicago, there are black residents who wouldn't mind seeing thousands of gang members locked up. It would not be surprising to hear sentiments similar to Kirk's coming from black conservative political figures -- such as Herman Cain, a tea party favorite, or Sen. Tim Scott, R-S.C., who has a near-perfect rating from the American Conservative Union. Rush didn't question Kirk's expertise when he voted to expand background checks for gun purchases, which Rush also supports.
For Rush to now dismiss Kirk because of his background is no more legitimate than it would be for Kirk to remind everyone that Rush was a leader of the violent Black Panthers and spent time behind bars on a weapons charge. Neither approach addresses the real problems of crime in Chicago.
The congressman has every right to decry the substantive shortcomings of Kirk's proposal. But those shortcomings would exist regardless of who made it. What he has no business doing -- what no one has any business doing -- is using patronizing language that disparages an entire race.
Rush wouldn't quietly endure insults like that directed at him. They are no more tolerable coming from him.