Showing your penis is not honesty. That’s forcefulness. She did not lie to him. Kissing is not an acquiescence to sex. That’s like assuming that since a person is willing to have a one night stand with you then obviously they are willing to have sex bdsm style. No…that requires clear and respectful communication.
She didn’t ask to see his penis. That was unsolicited and absolutely inappropriate. Had she asked him to show it to her that would be a different story, but it’s not a different story.
Your responses seem to indicate some very concerning views on what’s acceptable behavior. Even if she had lied (which she didn’t), it does not justify his behavior. There is NEVER a scenario where that behavior is acceptable.