how does benedick decision to challenge claudio represent a major change for his character in act 4?

Benedick used to be on the side of men when it came to a battle of the sexes. After the slander of Hero, Benedick finally proclaims his love to Beatrice. This now firmly puts him on the side of women, especially in this case. Benedick thinks Hero is innocent and, more importantly, he will now back Beatrice to the end.