I think it’s likely that the process of discussion can be nonsense when the argument itself is valid. Reminds me of Swift. Perfectly possible to crack an egg whichever side you want doesn’t mean the war isn’t nonsense.

I’ve written on trans issues a few times. Always from a liberal perspective, almost certainly shaped in part by a childhood spent reading Pratchett. I don’t think he cared - I think he just told stories, I don’t think Gaiman cares either. His nonsense comment seems a defence of the good character of his friend. There are rabid idiots on both sides and both sides will likely lay claim to his work. I suspect Pratchett would be appalled by the nonsense found on both sides and the process.