it's definitely harassment but how is that sexual harassment...?
that was the asker's phrasing and not mine. that said, there is absolutely a sexual element to this harassment — not "sexual harassment as in i'm making it clear how much i want to fuck you", but "sexual harassment as in i'm publishing a list of relatively normal nsfw tumblr urls out of context in a way that is clearly intended to paint you specifically, especially in the context of what much of twitter thinks of trans women, as a deviant who cannot be trusted".
it's using sexuality and status as a sex worker against her. that is something which happens to me, fairly often — i am not a trans woman, but i was a sex worker for nearly a decade and sexually exploited/trading sex for favors well before 18. people get very twitchy about an ace lesbian who's fucked a four-digit number of men for a variety of reasons, especially a southeast asian migrant sex worker. i don't personally see it as sexual harassment when it happens to me because it doesn't make me feel sexually shamed, but i do see it as sexuality-based harassment, bigotry (consistently racism in my case, and transmisogyny here), and whorephobia across the board.
i think that it would be more than reasonable for avery or anyone else facing this behavior to feel deeply, personally violated by the ceo of a massive company pulling sex-related urls from empty old blogs (a private, personal thing) out to effectively tell the world "look, i'm being reasonable, here's a pervert, look at this perverted sex behavior, this justifies any and all mistreatment of her".