Yes, Sora, Yukiko's delinquent boyfriend is "super weak" because Yukiko was able to lay him out in public while he was approaching to help her.
NOT because he, being a decent fething human being, isn't going to go "HULK SMASH!" on anyone who touches him, especially his girlfriend whom he feels exceptionally protective of, and instead let himself cushion any impact that might come from her tackling him.
Stupid bint.