Yes, I know what an emdash is---I've been using them in my writing since long before they came to the fore of the AI writing conversation. Anthropic's use of the emdash in the fragment I quoted is clumsy and reads poorly relative to the obvious alternative, a comma.

I didn’t mean to suggest you don’t know what an em dash is. But you said “this isn’t how you use them.” And my response is: actually, this use of them is totally fine.