I agree, that he is a shoo in for the other Olympics spot, both because there are only 3 realistic candidates for 2 spots and XX is already required for doubles.
But as for him being at his top level again, frankly, no. I don't think so. I think he's definitely getting back on the right track now, but there is still a bit of work to do. That said, he has such depth of talent, that I don't think he necessarily needs to be at his absolute top form. But I don't think he is at it.
The reason I don't think he is at his absolute top form, is because of the way he opens up most of his points these days, with short pushes.
While there is nothing intrinsically wrong with short pushes, it is a more passive way of playing. Pretty much every match he plays lately, his push rallies have gotten shorter, and he has come up with the first attack more often, which is why I think he is on the right track. However, his success rate on those attacks to get out of the short pushes have so far not been fantastic.
The game based on a more aggressive over the table game is inherently a more assertive one, where you take control of the flow of the points. When you are playing well, it is also a far more dominant playstyle (eg FZD last year). I think right now, he's not just choosing to play a more passive style, but judging from his error rate on the first attacks, he's actually not able to play as dominantly as he used to. I think this shows from how much more vulnerable his game looks now, compared to how untouchable (except against ML) he looked last year.
So I think he's probably on the right track, but no, I wouldn't say he's at his top level.
FZD worked on short pushes because it was a part of his loss against ML, especially at 2017 WTTC. He was too hasty attacking the first balls and making mistakes. His short pushes are not a sign of vulnerability. But a sign of wisdom. He had a hard time changing his game that is for sure, and it may have cost him the WTTC 2019 loss. But he is now back on track and proving in this TWC he's the best choice for 2nd singles spot in Tokyo.
I would've really love to see XX vs Jang Woojin today. This was a real chance for Korea. But against FZD, there is just no suspens.
As a coach who would you rather have in the arena? There you have it...