Why would a Cylon Basestar (and Raiders for that matter) have life support systems? Sure you can say for Baltar, but I'm sure he wasn't in the thought process when the Empire designed and constructed them. For the Leader's pet lizard? Seems unlikely, maybe the throne room for him to live in, but every support ship?
I could see a case they had some areas with life support for prisoners to be "cared" for. But again, every Raider, landing bay, computer core, full on throne room and little one later for Baltar? Seems odd. Why all the effort and energy for O2, heat, and such that machines do not need?
My best retcon explanation is the original Cylons designed the Basestars, Raiders, everything. Clearly they were living beings. As such the Centurions, IL Series and Leaders were just used to being in it, and the systems being up and running all the time since everything the Cylon Empire makes is super advanced and just THE BEST darn space stuff, ever.

What do my fellow Centurions think? Let me know.