case, the major difference to me is that it was also evidence of a crime, not only used to assail his character (though you could also argue that in this case it was also potentially evidence of Congressional ethics violations?).

I'd actually say that the evidence of a crime is why and where I draw the line. Something being "unwanted" isn't necessarily illegal, and something can become unwanted after the fact, etc--or somebody can just misread a situation (I.e. two parties send very flirty texts back and forth and one of them "escalates" the conversation). If AW were conversing with an adult, I'd say he was a victim.