Here's the definition of a "force out" from the USSSA rule book:
FORCE OUT refers to when a Runner is tagged by a Fielder with the ball (while on or off a Base) or a Fielder holds the ball on the Base to which a Runner is forced to advance before the Runner can reach that Base and before any succeeding Runner is put out.
Here is their actual rule:
Base Runners Are Out Under The Following Circumstances: (8-5-N) When, on a force out, a Fielder tags him with the ball (while on or off a base) or holds the ball on the base to which the Base Runner is forced to advance before the Base Runner can reach the base.
I don't see how you could interpret this any differently than every single other baseball of softball organization does.
Link to USSSA on-line rule book:
USSSA Slow Pitch Rule Book
Maybe when they called the "home office" the janitor answered the phone...