THE PLT OF A NORTH AMERICAN T-6G, N1364J, HAD JUST LANDED & WAS TAXIING DOWN A PARALLEL TAXIWAY TO THE APCH END OF THE RWY TO TAKEOFF AGAIN. AT ABOUT THE SAME TIME, A CESSNA 150K, N6402G, HAD BEEN STOPPED AT THE INTERSECTION OF THE PARALLEL TAXIWAY & ANOTHER ADJOINING TAXIWAY. THE CESSNA 150 HAD BEEN STOPPED SO THAT THE INSTRUCTOR (CFI) COULD GET OUT OF THE ACFT & THE STUDENT COULD PROCEED WITH HIS 3RD SUPERVISED SOLO. AS THE T-6 APPROACHED THE INTERSECTION WHERE THE CESSNA WAS PARKED, THE T-6 PLT MADE A SHALLOW S-TURN TO THE LEFT, THEN S-TURNED BACK TO THE RIGHT. AT THAT TIME, THE LEFT WING OF THE T-6 IMPACTED THE EMPENNAGE OF THE CESSNA FROM THE LEFT REAR. THE CFI HAD JUST DEPLANED & WAS STANDING ON THE GROUND NEXT TO THE CESSNA. HE WAS KNOCKED OFF BALANCE & GRABBED THE STRUT TO KEEP FROM FALLING TOWARD THE PROPELLER. HE THEN FELL UNDER THE CESSNA & INJURED HIS KNEE. NONE OF THE PLTS WERE AWARE THAT THE COLLISION WAS ABOUT TO OCCUR.