Rule 4 - Section 30 . Article 2
To establish or maintain legal rebounding position, a player shall not:
b. Extend either or both arms or elbows, fully or partially, in a position other than vertical so that the freedom of movement of an opponent is hindered when contact with any of these body parts occurs.
d. Violate the principle of verticality (a player is entitled to his/her space that is occupied, plus all vertical space above that player).
Omier committed a foul in two different ways before Cunningham could commit a foul. The first action occurred when Omier pushed Cunningham into the restricted area. Not only was his second action a foul despite endangering himself more than Cunningham, but he endangered himself because it was a foul. If he had merely jumped vertically in his own vertical space rather than into Cunningham's vertical space, he would have fallen more safely, if at all. This seems like a clear example of refs misapplying the rules because they don't want to catch heat for calling a foul on the player who is more endangered, even if he put himself in that danger. To those arguing, "the refs always call it this way", then they're always calling it wrong. Also, read some David Hume.