I've copied and pasted the post below. And figured out it was probably Prince Gabriel myself. I may be wrong, but the birth dates match up.
"The Trans Woman Who Killed Rasputin:
Today in Transgender Historical Recovery, let's talk about Princess Yusupova, the trans woman who killed Rasputin. I won't dead name her in this piece, but I'm sure you'll be able to find her name if you look, and verify the facts I am about to relate.
Princess Yusupova was born in 1887, and made clear in her memoirs that her mother raised her from the age of five in pink dresses. I actually think this is a twist on a child's insistence, and I think the evidence comes for that from a couple of places.
In the first place, Princess Yuspova, starting at age 12, would frequently wear gowns, furs, and jewels, to attend balls and parties in St. Petersburg. This first outing was met with stern punishment and disapproval from her father, but it did nothing to dissuade her from wearing women's clothing. According to her own memoirs, she even attracted the attention and amorous advances of Great Britain's Edward VII while abroad.
And she wasn't merely cross-dressing, or gender non-conforming. She made plain her desire to transition, medically, in the following section in her memoirs:
"I was ashamed of my skinniness, and longed to find a means of fattening out. Then, one day, I happened to see an advertisement which gave me high hopes. It extolled the merits of Pilules Orientales, a French patent medicine warranted to turn the flattest breasted lady into a harem beauty of opulent charms. I managed to get hold of a box of these pills and took them on the sly, but, alas, without result. The doctor who attended me saw them in my bedroom and asked what they were for. When I told him of my disappointment he was much amused, but advised me to discontinue the treatment."
The subtext in this is so clear it's almost painful. Here she is, taking medication to grant her a bust, which fails, as hormone therapy was still a thing of the future. But the desire was so strong she wrote it in her memoirs after a life spent forced to live as a man.
The evidence seems to indicate she stopped going out in women's clothing after one last scandal in 1908, at the age of 21, but this accords too with the expected post-pubertal changes which would have made passing difficult. She would kill Rasputin 8 years later in 1916, and would then live a long life, married to a woman, fathering children, like most pre-modern trans women.
It's interesting to see that no-one has ever mentioned Princess Yusupova's obvious trans womanhood in print before, despite herself having left all the clues in her memoir, and in her letters, and in the letters written to and about her. This is the difficulty that I and other trans women have with cis people who are content to try to erase the transness inherent in the persistent behavior of living a double-life as a woman for a decade, and in trying to take pills to grow breasts. But, I'm sure like the Vicountess Cornbury, there will be plenty of cis people to line up and say that this sort of thing doesn't make you trans."
The only Gabriel Yusupov I can find seems to be alive and well living as a dentist in Queens, NY. Prince Gabriel Constantinovich was a Romanov, not a Yusupov, and he had nothing to do with the assassination of Rasputin.
The only Yusupov to be born in 1887 was Felix, who was indeed outed as a high-society cross-dresser in his youth, may have been bisexual (he denied it), and was (probably) the ringleader of the conspiracy to assassinate Rasputin in 1916. The quoted passage is indeed from Felix's 1953 memoir Lost Splendor (the opening paragraph of Chapter 5), it's not a fabrication. I haven't actually read the memoirs myself, but I see no reason to doubt the basic claim that Felix liked wearing women's clothing in public, it's corroborated in several other places. I can even accept that the quoted passage means exactly what the post you're copying says it means, but anything beyond that has to be speculation.
I won't get into the issues of deadnaming, what constitutes a trans person, or historical oppression of transgender identities, here. Instead I'll warn against projecting modern social mores and ideologies onto people who lived even as recently as the subject in question. I totally understand the desire to claim historical persons as a part of one's own contemporary community, it engenders (no pun intended) an unavoidable air of authority and validation, but doing so is often fraught with superficiality, miscategorizations, and outright bad history.