When the person ahead of you in the store que is typing in their bank card code and you notice you can see it if you look closely, you are still a fucking arsehole for reading that code, use it or not, whatever, still a dick move, and this fucker even took actions based on similarly gained information.
Or like a boss of a company goes and looks at your social network profiles and then brings that up when you go talk to them about that raise you should have gotten long ago but never got. That's a bit more public info even but still a dick move.
I think you should re-read Chapter 5.
While talking to MC, Kaido asks him to show his skill list which MC does openly allowing Kaido to read it, but he only reads it partially and gives up upon seeing MC's Level.
Kamishiro is beside them while it's going on, and is also able to see it (since Status Windows are see-through transparent).
If i have to say, the situation was more like MC showcasing his Status Info like a Banner in a public place for everyone to see.
So, it was more his fault for being careless than for other people reading it.
Or in the analog of bank card code, it was like he was shouting his number out loud while around everyone.