After the final whistle went they'd have known...all of them including Allardyce.
It's a pretty dire team spirit we have if all of them aren't 100% looking for justice.
Did Allardyce think in any way it was debateable?
What is it you want him to say? Accuse Firmino outright without knowing the facts. Im sure the whole club believes Mason but he cant go blindly throwing accusations out himself when he was nowhere near it