Out of Bounds Question
 

I'm new to officiating and I was officiating a very close game in a gym where the walls of the building were about a foot past the baseline. A-1 had just got the ball from a pass in the corner and was defended by B-1. A-1 had not dribbled, and Team A had a man advantage as some Team B players were slow to get back on defense. B-1 touched the wall and slapped the ball in A-1's hands. I called out of bounds Team A ball. Team B coach was furious, saying "he cheated," he swore that's not what the rules say, and has "seen it more than once before and I'm wrong," finally saying it should somehow be a tech. My partner and I talked and we both agreed on my call. Is there any rule about a player "forcing" an out of bounds?

Also, the most upset I've ever seen a coach about a call in his favor.

Another Brick In The Wall (Pink Floyd, 1979) ...
 

Let's keep it simple. B1 touching the wall (which is out of bounds) and the ball at the same time means that B1 is called for an out of bounds violation, with the subsequent throwin going to Team A. B1 touching the wall out of bounds is the same as B1 touching the floor out of bounds.

To be out of bounds, a player must touch the floor, or some object, on or outside a boundary line. People are not considered to be objects, so inadvertently touching someone who is out of bounds (another player, a photographer, a coach, an official, etc.), without gaining an advantage, is not considered an out of bounds violation.

Slap Leather (James Taylor, 1991) …
 

If A-1 had been in the act of making a throwin, and if B-1 had crossed the boundary plane and slapped the ball from A-1 hands, under those specific circumstances it would be a technical foul on B1, but obviously, that's not what happened here.

Yep another coach who “knows “ the rules. ... his argument was probably the first indication you got it right ;)