You can tell them that you would rather write about someone cool like an empress rather than someone pathetic who only ever rose to the ranks of Prime Minister. If Margaret Thatcher had been half the woman with half the ambition of Empress Wu Zetian, she would have done a coup d'etat the queen of England, ripped the crown off her corpse, and reinstated absolute monarchy in England. Instead she meekly settled for Prime Minister. Pathetic.

I lol'd at this, especially keeping in mind that this family member of mine thought Margaret Thatcher was so iconic to have risen to power in a patriarchal world (like Wu didn't do the exact same thing).

Unrelated but have you read Iron Widow by Xiran Jay Zhao? It's at like the intersection of sci fi and fantasy and is directly inspired by Wu Zetian. I also think it's a book all leftists should love because it's very much a revolutionary story that rejects every bullshit defanging and subversion that Western revolutionary stories put in to sabotage revolution (For more on those sabotaging tropes: https://redsails.org/the-swerve). If you haven't read it I cannot recommend it enough. It's so damn good.

My friend actually introduced this book to me after I told her I'd be studying Wu! Strongly considering reading it now that you vouch for it, too.