As someone who grew up with the 1990 TV series version of the Moomins, and also reading the books once I was in my teens, the idea of a group of Hattifatteners asking for cocktails feels completely out of place.
Those guys move in swarms like a force of nature, do not speak, and feed on lightning.
I only read the books, and it's been quite some time. I had forgotten what the Hattifatteners were called. Didn't they trap the Hemulin at the the top of a pole once?