Whoa Whoa - Dead Ball or Not?

[JPaco54]

New one for me. I am BU in C. R2 trying to score on hit to LC. Throw to the plate, R2 slides, catcher goes down to his knees in front of the plate to block the ball on the one bounce throw from Left. Catcher bobbles the ball as he is leaning towards sliding R2. Catcher ends up laying on R2 as R2 slides and stops short of the plate. R2 is 1 foot (12") short of the plate. Ball is laying on the ground. As R2 scrambles to get to the plate, the PU yells...WHOA WHOA and both players stop their movements. Def. Coach "yells tag him tag him." Catcher picks up the ball and tags R2 and PU calls him out. Offensive coach protests that PU stopped play by yelling Whoa Whoa therefore you can not call R2 out due to Dead Ball. PU comes to talk to me and says I thought the two players were going to start pushing each other so my natural reaction was to yell Whoa Whoa and I know I should not have done that. NOw what Do I do? PU ended up letting the play stand. R2 out on the tag. Off. Coach disagreed but did not make a big stink about it. (Later learned he was a HS and Small College Ump.) We played on. Reviewed Rules and Case plays later that would help in making the right call on this play but came up empty. Any Suggestions on what may be the right call on this or did PU do right? Thanks!