Does not sound like assault to me.
From what the New Yorker article said, if any assault occurred, Ms. Ramirez was the perpetrator, not the victim. If someone exposes themselves in your view it does not give you the right to touch their genitals. What Ms. Ramirez did was no different than someone who reaches out and touches a dancer at a strip club.
From what Ms. Ramirez allegedly remembers, at a wild party somebody decided to expose themselves, much as a stripper would if they were performing at a party. She should have left, or even pushed them away without groping them. But, assuming her memory is correct, she chose to touch their genitals. Unless the other person consented, that's a sexual assault by Ms. Ramirez.