I would never take sperm from someone without their prior consent. Violation IMO.
ExDH and I still have a frozen embryo from when we had to undergo IVF with DS1. We had to sign forms at the time, stating what we would like to happen to it in the event of one of us dying. We both agreed the other could use it, to help provide a full blood sibling to DS1 if we chose to. This was of course assuming we were still married!
I highly doubt a doctor would remove sperm from a man without prior consent. Can this really happen?! What happens to his family with visitation and access etc very messy situation,