W.T.
I am probably not the person you want answering b/c we cosleep with our 9 month old and our 2 1/2 year old sleeps in his bed in our room and climbs into bed with us or we climb in with him quite often. It's not for everyone, but it works.
In my opinion, children up until a certain point don't have the tools they need to deal with what comes up for them and when there are lots of changes, we rely on our wisdom and experiences to accomodate those changes. Sometimes we even struggle through. Your son doesn't have any of that. He needs your support.
I guess what I am trying to say is do what you think your son needs. If he needs to sleep in your room for a while, then do it. It doesn't meant that he will be there forever or through high school. It just means that he needs to do it right now. In a week, he may be ready to go back to his room consistently.
My friend's 9 year old sleeps frequently on a mattress on their bedroom floor. She struggles with it, but told me once that she didn't want to be alone at night and feels secure knowing there is someone right there. Why shouldn't her son have that same sense of security.
You will hear from both sides....the "your child must sleep in their bed every minute of the night" camp and my "family bed/room" camp. Do what works for you. There is no right answer. If you think sleeping on the cot at the foot of your bed is what he and your family needs, then do it! You are ultimately the one who makes the decision, not those of us who don't live in your house.
If you want permission, then you have it from me. I honestly know more people who admit to a child sleeping part of the night in their room or bed than I know people who insist on their child remaining in their room.
Good luck mama!