Can't you?
I do not have enough information to be able to judge what the actual facts were out of several possibilites. LaRussa often does things that I do not understand. That's probably why he's a major league manager and I'm not. One possibility is the it was very late in the inning, the last pitch or two of, I think it was Encarnacion's at-bat when LaRussa was just beginning to be made aware of what was happening. The inning did end very quickly, and perhaps it was before he had much of a chance to think about it and decide if it was credible enough to warrant stopping the game. I don't know. I do know that LaRussa does not like 'showing up' the opposition, for what it's worth.
I also don't know why Rogers lied. It may have been simple gamesmanship, as been suggested, or it may have been because he was actually cheating. Again, I don't know.
Cordially,