I'd like to know who told him this. Was it Riley? Or another official? If so, then it is a deliberate attempt to manipulate games for commercial reasons, and can have far reaching consequences.
If Mane's reprieve yesterday was due to some sort of enforced leniency, then Mane skips a three match ban. He has already scored against Chelsea when he should have been dismissed. What if he scores in his next three games? What if Liverpool win by a single Mane goal? What if the defeated team gets relegated as a consequence of that goal?
Gallagher is right though. You can't send a player off in a high profile game unless there is no other alternative. He should have added "or any game". The law is clear, and in the Mane case, there was no alternative. It was serious foul play, so should have been a sending off. If Taylor didn't see it as serious foul play, VAR should have asked him to take a second look, as it was a clear error of judgement by Taylor.