Being a volunteer manager can be a thankless task.
I remember having to report a volunteer to ours for racist comments. Of course it was a volunteer who had been involved with the charity since it's founding and was massively popular with all the other volunteers.
The comments were likely normal for his social circle but absolutely beyond the pale for a professional environment and there were multiple witnesses.
It caused total uproar as basically the whole volunteer body felt he had been badly mistreated and all the staff were upset by the racism and wanted him to go.
With very long term volunteers they can feel some sort of ownership of the organization but of course over decades, everything changes.
That said, if this elderly lady simply asked why pronouns were now interesting, it's a massive over reaction by the charity. I think the PP who suggested there was more too it and the charity wanted to get rid anyway has probably nailed it.