I do think your DH's reaction was inappropriate though.
How is becoming emotionally upset when faced with the sudden possibility of his father's death inappropriate?
He did not yell/scold/say anything negatively towards FIL. All he did was try to call him and leave messages saying to call him back. I really don't see where you are coming from with this one.
Well from the OP it really sounds like your DH made it all about him. And as I said in the post you pulled that quote from, I think FIL made clear the method he wanted to communicate - electronic, not phone calls - so "subsequent calls" - I note that's plural "calls"
- means your DH was pretty much trying to railroad over his father's wishes and enforce how
he (DH) wanted communication to take place (phone calls), and certainly your DH was trying to railroad his father about when
communication took place (right that second and not when FIL was ready to talk about it).
As scary and tragic as it may be to hear one's dad is ill, your DH needs to realize this isn't about him. Your DH isn't the one who is sick. Your DH's role is one of supporting cast not as the star. He should follow his dad's lead and not try to push his own pace and preferences.
So I think breaking down and then repeatedly calling someone over and over who has made it clear by their actions they don't want to deal with phone calls was inappropriate of your DH. Not cruel, not horrible or hateful, just inappropriate.
Over the weekend DH and I learned that my FIL has been diagnosed with a rare type of cancer...when we read it on his Facebook page.
I'm very upset about the way he decided to break the news. DH pretty much had a breakdown over the news (which left many unanswered questions) combined with the fact that FIL didn't even bother to call him and tell him. To make it worse, FIL did not answer any of DH's subsequent calls, and only sent him a brief FB message to give like 2 sentences more info on the diagnosis.
DH and FIL have a good relationship, no past tension or disagreements. I understand that FIL is probably depressed, but shouldn't he have at least called DH and told him instead of announcing his illness online?