The players are ultimately told to disregard what was said, not let it affect their gameplay, and not to discuss it with the other players.
Viewers have been told in the past that when stuff like this happens, houseguests are pulled into a room with production.
The Big Brother All-Stars cast seems largely jaded by the fanbase in general, so the last thing they’d want is to roll the dice and trust someone who ultimately just wants the game to be more interesting.
It doesn’t entirely squash conversation, but it does enough that players often can’t effectively strategize around the intel given, which they may be wary of in general.