Sexual assault falls outside the boundaries of normal youthful behaviour. Ford’s allegations assert that he deliberately pinned her to the bed and covered her mouth to prevent her screaming while he attempted to remove her clothes.
This is not normal teenage behaviour. It shows that he knew he did not have consent. Her attempts to scream showed that she was in an extremely uncomfortable situation and his attempts to stifle them were calculated and evil.
Also, where do you draw the line. The second set of allegations of sexual misconduct, made by Deborah Ramirez, refer to an incident when he was studying at Yale University. Surely nobody would argue that this incident should be overlooked because he was still in the throes of youth?