Flop / No contact / travel

[Y2Koach]

Team A is losing by 20+ (score probably doesnt matter). Team B's first unit has taken several good charges in help defense on the baseline throughout the game. With about 3 minutes left, Team B puts subs into the game. A1 beats B1 along the baseline and drive to the goal. B2 comes over to help and sets up to take the charge. A1 anticipates the charge and pulls up for a jumpshot as B2 begins to fall backwards anticipating a charge. A1 senses that he might land on B2 and braces for an akward fall, never releases the ball for a shot. How should this type of situation be officiated? thanks.