The best part about kids is having this talk. "Because they want to." "Oh, okay." Kids literally don't care because they have no reason to think it's odd or strange unless you act like it is.
Let me preface the post to follow by saying that I am not worried (like the poster you responded to) about my child walking into Disney and seeing a man dressed how a woman would typically dress. I appreciate having open dialog with my child. I would prefer they ask me rather than someone else seeing as I am ultimately responsible for them. That said...
1. If it was not odd or strange to see someone dressed in this manner than the child would not ask the question in the first place. This negates the premise that how I act will determine whether my child finds it odd. They found it odd hence the question. Otherwise the question is not needed. I would agree that how I act could determine whether or not my child may accept the way the person is dressed as "ok" or should be viewed as "normal," but the question is spurned by the fact that my child finds it odd for a male to dress how the typical female may dress.
2. My 9 year old is exceptionally inquisitive and is not going to accept the "Because they want to" answer as a real answer. It will not satisfy her curiosity because she is intelligent enough to know that "because they want to" is not a real answer. She would be curious as to why I chose not to explain the issue and either continue to ask or file it away to be dealt with later. Children know when they are being dismissed just as well as adults do.
I do not mean this as a knock in any shape or form, but my assumption from your post is that you do not have children of your own? I obviously could be wrong, but your view seems to indicate that.
3. My answer to the question would be something like...
The person dressed in said manner has a condition where their brain perceives that they are female, but were given the body of a male. Consequently, they dress the way they feel most comfortable and what helps them feel better. I won't tell her how to feel about it. She will feel how she is going to feel. Children are much more intelligent than we often give them credit for.
4. I lean conservative, and I have my own issues with the policy but I realize that Disney is only evolving with the times. They are catering to a new generation who are creating new social norms and I may no longer be in their target demo. I am at peace with the fact that Disney is leaving me behind. I am thankful that I got countless years of enjoyment from their product and except that todays Disney is no longer my Disney. I will gladly step aside and let a new generation enjoy the "new" Disney. In fact, I was a 16 year passholder and made the decision to let my pass expire pre-Covid in 2020.
5. Whether I agree or disagree with someones lifestyle, I will always treat people who are different from me with respect. My hope is that my daughter will be kind hearted and accepting to others as well.