Man, this resonates with my brain. I kind of love the literal Hobbesian Leviathan. Obviously this also has heavy wickerman vibes.
I have a hard time thinking of this as an adventure as much as I imagine it as a monster. There really isn't a hook, or story here. It kind of feels like a trap? If the players don't engage it, nothing happens. There's no stakes. The people are apparently happy to be of a hive mind and cramming themselves inside this thing. I can see players wanting to save them from themselves, but that certainly isn't a given.
I think this would be strengthen as an adventure by a hook, like a missing family member who went to this village and the goal is to save them, which will of course trigger the Lord of Warmth at some point.
It would also be nice if there was a mechanism for weakening this thing before it's triggered.
Also, because of the wickerman vibe, I feel like this has to end with being on fire...