If you want proof that folks are using the phrase "sexual assault" differently than you likely are, check this out:
In California, a new bill would require colleges and universities to impose a mandatory minimum sentence for campus sexual assault: two years school suspension. The rule would apply to both public and private colleges that rely on state funds for student financial aid, the same way California's affirmative consent measure operates.
My definition of sexual assault is rape, that is either using force to have sex with a person who is unwilling or having sex with someone who is physically incapacitated. By my definition, the penalties established by the California bill are absurdly lenient, particularly since California law already establishes a penalty of 3-8 years in prison for rape.
What is going on here is that opponents of certain other behaviors -- sex while drunk, sex that is regretted later, and possibly even speech that is hurtful to women -- have lumped these behaviors into the term "sexual assault" in order to try to increase the punishment for these things. In California (on campus but nowhere else) sexual assault is "a failure to obtain ongoing, enthusiastic, affirmative consent at each stage of a sexual encounter"
This is a verbal tactic is increasingly common -- note the trend to many colleges to try to label unwelcome speech with which one disagrees as a physical assault or threat. But it has decided risks. While the intention is to increase the punishment for unenthusiastic sex to rape levels, the effect can easily just be the opposite -- to reduce concern and punishment of rape by watering down its definition.