No, they weren’t; my friend’s base is in D 10. Followers don’t take damage from temperature now anyway. Although I have died to meteors, I have seen my thrall shake it off like it was nothing. They would have to be hit by multiple meteors in succession to kill them that way.
Also, if you are testing in single player, you are testing it wrong in my opinion, you need to have a thrall that is NOT in your clan and then do the things you are suggesting. As long as the owner is not nearby, thralls go into a nerfed state as I have shown here: