Dropped Ball After Tag

[harmbu]

FED. R1 is stealing second. The throw arrives ahead of the runner and F4 applies the tag. As F4 is lifting his glove to show that he has the ball, R1's helmet contacts the glove and the ball comes out. BU calls the out. After the inning, BU was asked if he stayed with the out because R1 knocked the ball out after the tage. BU says that he did not see the second contact, but he had the out because F4 controlled the ball throughout the tag. He said that F4 did not have the voluntarily remove the ball from his glove after a tag like he would have had to do after a catch.

Any opinions.