To respond more seriously to his tweet; he seems to be responding to the IGN article and the general sentiment that some people are not happy about the price of the game. I think his response is honestly gaslighting and not helpful, but what he's saying is probably true also from a limited perspective.
He's an animator, and it looks like he's worked on God of War (2018), Resident Evil 7, Injustice, and other games. From the perspective of literally just the animation work alone, I'm sure it's very meticulously crafted. Everyone knows that Naughty Dog basically have the most attention to detail on animations of anyone in the industry other than Sonic Team. Of course if he's never worked on a Naughty Dog game, then the animation work is going to be on a level of detail he hasn't previously worked on.
But I just don't think he is personally saying that this game is the most impressive and difficult thing he's ever worked on as a whole when considering the whole project, when compared to other fully original, new video games like God of War (2018) or even Resident Evil 7 rebooting the entire series in a new perspective and having VR (both games were $60). I don't think anyone is claiming Last of Us is going to be a shoddy, cheaply made product without AAA production values. It'll have top tier production values. People are just being critical of the price in comparison to previous remakes, the reusing of the voice acting and motion capture work, the lack of multiplayer, and repeated releases for this game and the TV show even. His response pretends none of this exists and just narrowly focuses on his animation work, and is kind of missing the forest for the trees.
The game will still sell millions and I think it'll be a huge hit. But people have a right to be critical of aspects of the project if they want, and his tweet does nothing to negate that.