It doesn't need to be airtight for it to be an issue. If there isn't proper ventilation then too much smoke will remain in the hut, which can be harmful. As long as he doesn't obstruct the opening, it should be fine, but if he puts a door on it the hut will basically turn into a smoker and they will slowly suffocate in their sleep if they let the fire go during the night.
Just saying if I was there sleeping in that house I would die. I would just roll into the fire my body moves at night so it’s not common for me to fall of my bed
@Dazdigo for some bugs it does more the thought for ppl not like it works. Like you would rather sleep higher in the air instead of the ground ge5 what I mean. Also worms and legless bugs can’t ge5 up