I posted the rule. No one seems to care. You can't pull a player, only push from behind.
SECTION 3. Blocking, Use of Hands or Arms
Who May Block
ARTICLE 1. Players of either team may block opponents, provided it is not
pass interference, interference with the opportunity to catch a kick or a personal
foul (Exception: Rules 6-1-12 and 6-5-4).
Interfering for or Helping the Ball Carrier or Passer
ARTICLE 2. a. The ball carrier or passer may use their hand or arm to ward off
or push opponents.
b. The ball carrier shall not grasp a teammate; and no other teammate shall
grasp, pull, or lift the ball carrier to assist in forward progress. (A.R. 9-3-2-I)
c. Teammates of the ball carrier or passer may interfere with opponents by
blocking but shall not use interlocked interference by grasping or encircling
one another in any manner while contacting an opponent.
PENALTY—Five yards [S44].