The lack of any real source + the minor changes to headshape and the clothing damage mean it's probably safe as copyright law is concerned
I do think some memes would need approval a situation where they're effectively being sold. I'm no expert but, for example, I think Epic could use Drew Scanlon's Blinking Guy meme in a video no problem, but if they just made a digital Drew Scanlon someone at Giant Bomb or Drew himself could probably take that to court if they wanted to.
Big Chungus meanwhile would probably need WB's approval no matter what.