Lol this wannabe mob got so into mobbing that he screwed himself over and made himself stand out. Actually, sounds exactly like this MC. He doesn't think everything through, even though he says he does. He's way too excited by the simple things, tbh. And he's too prideful to stop and realize his mistakes*. This MC is obviously just a Chuunibyo that never got treated, and so fully devolved into his Roleplay (like a D&D player that only socialized in his RP group while in character).
It's like the flashbacks where he says he's a mob character...only he's nearly twice the height of everyone else, has like 10x more muscles, and clearly stands out. People just wouldn't say anything because you don't upset the 300 pounds of muscle looming behind you. Ever.
*Nobody spills that much blood from their hand when they get hit in the gut, acting like you know everything without reports is obviously going to cause huge misunderstandings (which, as an aspiring Shadow Leader he should know), nuking low level targets is going to make you a target (you don't cast your Epic Level Spells to kill freaking commoners unless you're Evil and the Epic Level Spell turns them into undead minions), announcing that your the person working in the Shadows to everyone doesn't make you a Shadow Lord.