To set the stage, the Code of Conduct:
No bigotry.
We don’t tolerate any language likely to offend or alienate people based on race, gender, sexual orientation, or religion — and those are just a few examples. Use stated pronouns (when known). When in doubt, don't use language that might offend or alienate.
Your comment was:
When you say "there is no need for you to tell me" in your example prompt, are you implying that people don't have a right to know if the person they are dating is trans?
It was flagged as unfriendly or unkind. "Likely to offend or alienate people" leaves room for discretion; given the subject matter, and knowing that at least one person was offended, I decided to delete it.
And in part it seemed to me the answer for your question was already fairly self-evident, for instance the next sentence in the prompt is bold-and-italic, "That is your business", and the other paragraphs talking about not making Alice feel pressured to explain - so clearly this answer isn't suggesting OP is owed an answer from Alice.
Some feedback: "Are you implying that..." sounds kind of combative. This isn't usually how I hear people bring up points they're genuinely unsure about - often it's an indication of someone trying to start an argument. I'm not saying this is actually the case - what was apparent to me in the answer may not have been apparent to you - maybe adding more context before launching into the question would help. "You say X, does that mean Y? I'm not sure because Z / Just wondering for the general case / (some other reason you are asking)".
(As for the answer you mentioned, suggesting that being trans is "lying" is considered a transphobic idea, yes. But I would rather not discuss details about a different user's answer here.)