I dont think he is, you are telling such a powerful man who took down the beast titan SO MANY TIMES died by a mere blast? I say BULLSHIT
You need to understand that he took out powerful titans with agility and dodging their attacks. If he had been taking the attacks like a champ all this time, then your argument is valid. Otherwise, it's something that's a complete misinterpretation. A full geared US soldier can fight against multiple armed civilians with his quick wit, tactic, and training. However, it does not matter whether he has been doing that for a decade, two, or even three. Put him 1 feet away with a live grenade, and I bet you $100 he's dead.