This reminds me of an incident that happened to me before 9/11. A Muslim man, his wife, and son got out of a car. The woman had been sitting in the back, the young son in the front. When they came back out, he spotted me. I was sitting in my car which was parked close to his waiting on my husband to make a quick stop. He came over and proceeded to put his shoe on my car's bumper. If he needed to adjust his shoe, he could have easily used his own car, but I think he was trying to send me a subtle message that I had no right to sit in the front.
I think you are right. This is a message to Muslims.
I hope you “sat down” on the horn.