Here's the wording
I've always thought that I can only choose open squares but the above text does NOT say that.LRB 4 wrote:A player with this skill is an expert at stepping neatly out of the way of an
attacker. To represent this ability, his coach may choose which square
the player is moved to when he is pushed back, rather than the opposing
coach. Furthermore, the coach may choose to move the player to any
adjacent square, not just the three squares shown on the Push Back
diagram. The player may not use this skill if there are no open squares
on the field adjacent to this player. Note that the coach may choose
which square the player is moved to even if the player is knocked over
after the push back.
instead it says
1) I chose where to go, not the opponent
2) I can chose any adjacent square
3) I cannot use Sidestep if there are no empty squares adjacent to me
From 1-3 it is not derived that I have to chose empty squares. So I could chose to "bump" into another player, initiating a chainpush, even though there are empty spaces for me to go to.
I don't think this is the intent of the rule, but that's how it is written.