As a single fellow who has always enjoyed my independence, I think you should say exactly what you said in your message, “We want to be here for you, but we do not want you to feel as if you’ve lost your autonomy.  How can we do this?”  That’s perfect.

Since I have no experience with SCT, I cannot help you with any details of caring for someone who has recently had one.  I expect you will get a lot of information from his treatment centre.   No doubt there will be an emphasis on keeping him free from germs and making sure he gets his blood tests.  This would be on top of the usual things one does when caring for someone recovering from a major medical procedure.

Joe