Ohhh, that makes sense then.
And glad it's not as short as it looks hah but yeah, I was thinking they might try to rest on top. Maybe try to add some support underneath?
And you said the house is really warm, right?
So maybe you could somewhat do a compromise? Like maybe try either turning down the heat in the house or at least their room or just bring them outside during the daytime for a few days or a week to get them used to colder temperatures.
They should be fine just being stuck out there, especially with 13 of them and a heating pad, but at the same time, they may have a point that it might not be best to go from 70s to 30s, i forgot it was so warm. Or maybe that was someone else?
Anyway, you're probably anxious to get them outside ASAP but if you are really nervous about it, especially with the possibly sick chick, then take it slow and give it some more time, and let them out to play in the colder temps
I think they're not ready for no heat source but with a heat source it should be fine but feel free to take it slow and see how they do