"Yomi" and "Yomi Hustle" are much closer to each other than "Yomi" and "Trek to Yomi".
If I would hear Yomi Hustle, I would think it's a sequel / spinoff to Yomi card fighting game from 2015.
If I would hear Trek to Yomi, I would think it's an unrelated trademark.
You can disagree with me of course, and demand objectively verifiable criteria to be able to tell what is a trademark infringement and what isn't.
And this is understandable.
But as far as I know, the only institution that can determine that is the court, because as we can clearly see in this conversation trademark similarity is a very thin ice and it's very debatable what is an infringement and what isn't.
I would imagine that the author of the game is not willing to bother with potential court case, or Steam is taking measures to prevent potential conflicts in the first place, relying on their subjective vision.
And this in my opinion is very understandable as well.
I don't think it's worth a conflict that will not benefit any side and only drain their limited resources.
Yomi is also made by a very small financially struggling indie studio who I don't think would be very happy to be dragged into this.