"can i ask a question?"
"SUre."
"is our author a boobs loving dude? because every single woman who wants me seems to have big boobs. why?"
"... well why not?"
For a sec I thought the ship was named "Catastrophe"... and I was like, Who the F would choose that for a ship name?! Author also seems to have forgotten MC has lived 15 years in this world... if MC still lacks the common sense of this world, he's beyond stupid.
That has not much to do with the time he lived in that world. He grew up mainly as a commoner who obviously didn't know that since, like stated the panel you quoted, it's something classified. And when he got recruited by the royal family and got onto the airship, the topic of their secrecy didn't come up. Most people on there probably assumed everyone there would already know. That's hardly "beyond stupid".
so the MC will forever be an ignorant dumbass, great, I guess the isekai part is just to sell, because the "he can draw manga!" is not enough of an excuse for this to be an isekai