When FIL was dying, I had to summon XH home from his work offshore. He was home for several weeks, then, as the end drew nigh, announced he could stay no longer and headed off to a job in South Africa, telling MIL he wouldn't be back for the funeral. FIL died the following morning. MIL was devastated and leaned on me (quite literally) because he should have been there to organise everything for her as he was the eldest son.
When my DM was killed in a car accident, he was at home. It was more than obvious to me that if he could have been anywhere else in the universe during that time, he would have been. He did step up and support me quite a lot, but his heart clearly wasn't in it.
When MIL passed after we split up, he phoned me up and asked me all the questions that the undertaker should (and certainly was) have answered for him. Just before the service at the crem, he was in the pub having a pint. I was in the pub having coffee. He thought it was odd I wouldn't have a drink (I was drinking, which is beside the point - I wouldn't go to any funeral drunk!)
Nobody likes death or dealing with it. I understand that. However, I don't understand how you could deliberately be elsewhere when a parent is dying. I didn't understand it with XH and I don't understand it with your DH. I know there is nothing you can do about this. He has to make his own decisions, but I do hope that he won't end up regretting this. 