I kind of feel sorry for that cop. I know you were probably flustered. A lot of non-horse folk need simple terms. Using the specific pattern that is on your Appaloosa would probably have confused him less. If you knew nothing about horses and someone told you their horse was an appaloosa-colored Appaloosa, that would sound a little confusing, no? As for Grade, pretty much nobody outside the horse world knows what that means. Simplify for these people as "mixed". Everybody was probably all excited and stuff, so that accounts for a lot of the silliness.
I hope that guy didn't die...ugh. I never witnessed an attempted murder, but I have seen a motorcyclist get hit by a car. That was frightening. I also saw a head-on collision where one of the drivers died...lots of blood there. Not a pretty kind of thing to be witness to.