Looking at it from the perspective of the BO - he told her his routine before she moved the horse.
As a BO- I find it very frustrating when people do not listen or think they will change what was told to them during the interview process.
To the OP - mine are out 24/7 with nice shed. When it's rain/ice/snow I keep them in stalls, but when it's just cold (under 25 but no snow/rain) they are still out and I put blankets on. I think it's much more healthy for the horse to be out for the most of the time.