Also with Gladio, when did he have time to grieve for *his* father? Perhaps he's thinking that just as he seamlessly took up his family's mantle, Noct should be able to do the same. I mean, he's wrong, but he's not out of the blue.
I was actually discussing this exact matter with my friend on holiday; turns out I get even more about these subjects when I’m two sheets to the wind, who’d have thunk it. But yes the relevance of this mild detour is that even he didn’t clock that Clarus had died. Granted, he hadn’t seen Kingsglaive at the time (this was promptly amended), but still I don’t think enough attention to that is given in game. We get one vague mention of his father on our way to titan and then nothing more.
Yes, I know the story is central to Noct but at no point does Gladio even say anything about it because it is never brought up and like srsly, someone just give that boy a hug. They are all grieving the loss of their home, but this is these guys dads.
But yes back to the original point, i completely agree. The Amicitia’s are very proud of their duty and I think Gladio had already accepted the fact that there was a very real chance that that is how his father would go, it comes with the territory. So while it was no doubt devastating for him he knew as soon as Regis was announced dead, his father was gone too and yes it was sad, but he knew it was then his duty to step up even more so than he already had in a way.
So with him accepting his duty, you’re right in his head, why couldn’t Noct do the same? Not realising that despite the similiarities in the situation, they were so completely different. So while in a way it is a logical way to think, like you said it is inherently wrong which is what he failed to see.