Runner On Base

[Love this Game]

I need someone help. (NSA Rules Mens Rules)

I am an umpire and a player but I need help with this call ok.

R1 is on first Batter is at the plate. The batter hits the ball on the ground and the pitcher fields the ball in fair territory. R1 takes two steps off 1st base and the pitcher throws the ball to first.

R1 runs back to first base.

The first base man threw the ball back to the pitcher, the pitcher then runs over the and tags R1 who is standing on first base. The umpire called them out stating that R1 had to advance.

Now I was playing and my team was batting. I have been umpiring NSA for years, I told the umpire R1 can not be out because when the pitcher touched 1st base he took away the force so there is no reason now that R1 had to advance now.

What ever the rule is can someone tell me where this rule is in the NSA rule book.

PLEASE HELP ME!!!