[best]

Comments on your thinking...

As a sponsor, when I say yes, I am accepting a certain role I should uphold for the benefit of myself and for the person I am sponsoring.
He should call, I should call thinking... He should call if he feels a need to keep you accountable... all other times it should be you reaching out for help, guidance or support as needed. You want to play golf...come Thursday you call or sit by the phone doing nothing. You want it...don't wait for a call.
I commend him for being upfront with you as he feels he can no longer hold to his side of the agreement in a manner that he feels is in your best interest.

Your other thoughts show that you care about others
(health issues)
(he has a new sobriety date)

You can and should take him at his word and continue on with your recovery as you look for a new sponsor but in my own thoughts... I would keep an ear open and maybe give a call of a hello just to check on how he is doing when you find a new sponsor.

Hey...just wanted to check in with you and see how you are doing... I found a new sponsor and wanted to let you know.
Such will give you some practice towards being a sponsor for others and will allow you an open door so you can ask how he is doing.