St Skittles, the thug, was protecting his turf at RATL. Since it was dark, and raining, he thought GZ was just another thug following him on his home turf. GZ was as just as a shadowy figure to him as he was to GZ.
No he thought GZ was a creepy ass-cracker. If St. Trayvon had lived long enough to become an imprisoned thug, he'd likely have become an ass-cracker himself.