i dont know any spoilers but maybe he meant that he wouldn’t have put him in danger if it was him, because im pretty sure he has a plan about destroying the system or something like that. It means that J now will put himself in danger to save others because thats just who he is. By him being closer, now he can’t easily hide stuff
im conflicted! usually i hate it when the ML is mean to everyone else, especially if they mistreat or overwork their staff. i feel like he's just prickly and not cruel, though, so i'm more okay with it here. in some isekai, the MC is an office worker who dies cursing capitalism and cruel bosses, only to fall in love with a ML who is a cruel capitalistic boss...

Sorry for saking but What did he mean by "if i known he was j i wont let him get close"?