I agree. They should remove True Grit entirely.
Here's why: Graves' rework frontloads his damage, making him very bursty. So he's basically a ranged assassin now. People may not like the idea, but it's not inherently flawed; Nidalee and Ahri are sort of those, and aren't too problematic anymore (I know everyone's circlejerking about Ahri rn, I'm talking about from a design perspective, not a balance one. Also I know she's a kite mage now). The problem comes when you also give that ranged assassin tank stats for sticking into extended fights, making them way better at teamfighting than they ever should be. Hell, any assassin who's allowed tank stats becomes overpowered (Hi Ekko and Fizz). By removing True Grit entirely, you remove that problem, and you also take away a secondary problem: His clear.
Yes, his clear. Everyone thinks his knockback is causing his great clear, but his knockback is only part of the problem, and True Grit is the other part. Go into Practice Tool and try clearing with Graves. Then do it again, but let your True Grit stacks reset between camps. You'll take shit tons of damage. Removing his MR only doesn't affect this, as Gromp is the only camp that deals magic damage, but taking it away entirely will make his clear a lot less healthy, but not so bad that he can't even full clear effectively, something even Taric can do (believe me, I tried).
Of course, I'm not saying that this alone would put Graves in a good spot. It would probably gut him, if he isn't also given compensation buffs, but what it would do is make him balanceable, and I'm pretty sure that's what Riot wants to do here.