A six year old is both inquisitive about the world and capable of learning about it so I don't see any less reason you should be prepared to talk to them about TLS than any other topic they might express curiosity about.
You have to pitch things appropriately. A six year old who has just noticed that some of her contemporaries have penises and some don't probably does not want a diatribe about Trans Exclusionary Radical Feminism and if she's wondering about TLS she probably doesn't need an excursion on ECC Safe Curves, but with care to stay relevant and not just blast her with jargon she doesn't understand there's no reason any topic needs to be off the menu.
Please, someone show this to a 6 year old and let me know long they stay focused on the topic and how much they actually understand about TLS after reading this. It would be hilarious if this were a youtube video, too. Sorry but I just don't believe any 6 year old is going to be interested in TLS or really learn much except how to mispronouce "computer" as "Compugter".
You have to pitch things appropriately. A six year old who has just noticed that some of her contemporaries have penises and some don't probably does not want a diatribe about Trans Exclusionary Radical Feminism and if she's wondering about TLS she probably doesn't need an excursion on ECC Safe Curves, but with care to stay relevant and not just blast her with jargon she doesn't understand there's no reason any topic needs to be off the menu.