A man breakingma womans arm wou have white knghts and women calling 911 on him and he would be jailed and sued. Dont tell me it would turn out the same way or that you,wouldnt think its overkill. Gynocentric society would crucify him.
To your point, men have successfully defended themselves against assaults from women AND won in courts. I personally know of one, who used to laugh at "husband abuse" until he became a victim of domestic violence. Fortunately for him, other males chose to support him rather than play the role of the "white knights", and he actually won.
As for the "white knights", that's THE CHOICE OF MEN hoping to score with the damsel's in distress.