Chuck, you're 0 for 2 today, in my book!
A player can most certainly start a jump stop without either foot on the floor. And he can most certainly pivot if both feet are off the floor when he catches the ball.
4-43-2a
A player, who catches the ball while moving or dribbling, may stop, and establish a pivot foot as follows:
a. If both feet are off the floor and the player lands:
1. Simultaneously on both feet, either foot may be the pivot.
2. On one foot followed by the other, the first foot to touch is the pivot.
3. On one foot, the player may jump off that foot and simultaneously land on both. Neither foot can be a pivot in this case.
I believe you're ignorong the fact that 4-43-2a and 4-43-2b describe two legal and different ways a jump stop can be used.
BTW, Jim is correct. The NFHS Travel video has a very good jump stop segment in it.