Rush has addressed this several times. One of the black conservatives made a stink about it, but later apologized when he found out that Bush was blindsided. Bush was supposed to meet with Cummings, who brought Jackson along as an uninvited guest.
Limbaugh stated that this has happened to him on numerous occasions and you suck it up and be gracious and turn down invites from the people in the future.
Could you imagine the outcry if Bush cancelled because Jackson was there?