My daughter's room is warm. My son's room is colder than any room in the house. I don't know why. It just is. Does he complain about the temperature? No. He wouldn't complain if we let him wear shorts when it's snowing either. He refuses to cover up with blankets. If you cover him when he's asleep, he kicks the blankets off immediately. I personally think if he was cold enough then he'd cover up. My husband worries about him being cold though. Either way, I don't see it as a big deal really. Plus, I think it's a factor in why he doesn't want him to sleep in his room, but not the only factor. He misses him.
My daughter did sleep in the bed with us for a long time. She was trained to sleep in her own bed as an infant, started sleeping with us when she was a baby/toddler, and went back to her own room around 5 years old because I got tired of being kicked. She'll sleep with us every blue moon (if I tell her to crawl in bed so we can talk/cuddle and we just fall asleep) but she's older/bigger, is fine sleeping on her own, and our queen bed is just too crowded for my liking with 4 people and a dog. The bed was a lot bigger when they were 2 and 4.
I'm probably about to kick my son out too because he kicks more/harder as he gets bigger. He can sleep on the couch for all I care.
OR..my husband could go sleep in our son's room and my son could stay in the bed with me. There would be enough room that way, and nobody thinks there's anything weird about mothers sleeping with their children or even spouses having separate bedrooms. Go figure.