and are holding motionless.

If that doesn't happen, nobody is "set" yet and no false start can occur (see false start rule below).

What Boise does is called a "shift" and it is permitted specifically in the rules. You can just keep doing it till you run out of time. It is a simultaneous change of position by two or more players.
(http://www.dfoa.com/attachments/article/69/2013-14_Football_Rule_Book.pdf)

SECTION 22. Shift
ARTICLE 1. a. A shift is a simultaneous change of position or stance by two
or more offensive players after the ball is ready for play before the snap for a
scrimmage down (A.R. 7-1-3-I-II and A.R. 7-1-2-I-IV).
b. The shift ends when all players have been motionless for one full second.
c. The shift continues if one or more players are in motion before the end of
the one second interval.

The false start rule is below:

ARTICLE 2. a. Shift. After a huddle (Rule 2-14) or shift (Rule 2-22-1) and
before the snap, all Team A players must come to an absolute stop and remain
stationary in their positions for at least one full second before the ball is
snapped, without movement of the feet, body, head or arms (A.R. 7-1-2-I).
b. False Start. Each of the following is a false start by Team A if it occurs prior
to the snap after the ball is ready for play and all players are in scrimmage
formation:
1. Any movement by one or more players that simulates the start of a play.
2. The snapper moving to another position.
3. A restricted lineman (Rule 2-27-4) moving his hand(s) or making any
quick movement. [Exception: It is not a false start if a Team A lineman
immediately reacts when threatened by a Team B player in the neutral
zone (Rule 7-1-5-a-2) (A.R. 7-1-3-V)].
4. An offensive player making any quick, jerky movement before the snap,
including but not limited to:
(a) A lineman moving his foot, shoulder, arm, body or head in a quick,
jerky motion in any direction.
(b) The snapper shifting or moving the ball, moving his thumb or
fingers, flexing his elbows, jerking his head, or dipping his shoulders
or buttocks.
(c) The quarterback making any quick, jerky movement that simulates
the beginning of a play.
(d) A back simulating receiving the ball by making any quick, jerky
movement that simulates the beginning of a play.
5. The offensive team never coming to a one-second stop prior to the snap
after the ball is ready for play (A.R. 7-1-2-IV).