I don't know what year/model Sportster you have but the one I was working on had this style caliper. All bolts are 12pt with the small middle ones, the pin bolts, set in a recess so they can only be turned with a socket and not a wrench. Five minute job it you happen to have the special tool which I don't and I doubt the average Harley owner has it.
As I remember, Harley once placed a magazine ad that informed owners to only use their brand of oil and that using other brands would void the warranty or even damage the motor. Once again I call BS.
XZN are high torque, strip-resistant fasteners and an acceptable application for that caliper. If you haven't seen these cap screws before you lead a sheltered life because they are everywhere and have been for decades. Cars, airplanes, tractors,, heavy equipment, air compressors, hydraulics etc all use them. If I had a choice my bike would use these over easily-stripped Allen or Philips fasteners