I'm sorry, but that's just plain strange on several levels. First, let's start with who you write for. That website administrator said you write for cisgender people, which contradicts my own experience with your writing, and I should know because I edit every piece you write for P&P.
You have always made it clear you are sharing your personal transgender experience and that people shouldn't make general inferences from it. I don't know if you've ever directly stated you're mostly writing for other transgender people, but that is always the impression that I've received. Strongly.
You embody the founding ethos of Prism & Pen: LGBTQ people telling their own stories in their own voices.
As to the website administrator's claims that you're ignoring a diversity of trans experiences, I can't count the number of times you have written that you know there are many different trans experiences and that you're only writing about yours because that's the one you know.
You have gone to great pains to acknowledge that, and did so again just recently.
You're telling your story, and that's a wonderful thing. It's not your job to tell other people's stories. If that administrator would like trans people with different experiences to share stories with P&P, ask them to drop us a line. We won't hesitate to publish.
In the meantime, I noticed that just this morning a trans person in pain has reached out to you asking for help. Obviously, your voice has meaning to people.
Keep doing what you're doing!