The NEU ( formerly the NUT) leadership have always been radical agitators....always bolshie and politicking in the staffroom.
At last year's Labour party conference there was a conspicuous number of UNISON members screaming abuse at women who had gathered to speak.
Many people who go into leadership positions in unions see the unions as a route to a political career and so these roles tend to attract the most ideologically and politically motivated. They are usually far more radical and bolshie than most of the membership.
My father used to be an engineering union shop steward. He saw his role as a mediator between workers and management - but there were always others, though, who just wanted permanent aggro and revolution.