and the initial intercept occurred at 30,000 ft., the F6F drone was probably doing less than 300 kts. The F-89D Scorpion was capable of just over 550 kts in level flight.
You'd have to be an 'Einstein' to calculate how to employ unguided rockets effectively under these conditions......oh wait.
(BTW in the apples and oranges department, 550 kts cal is 1.36 mach at 30K)