With respect to defining what's a damaging amount of use, they hold the advantage.
You'd have to make the argument that what you've posted cannot be confused for the original content, does not contain any remnants of the original content (which tracings blur even more), and could not be easily be distributed/monetized in a way that it could be confused for the product.
That's…pretty broad.
As mentioned previously, there are parts of this, I can't talk about. But there are certainly aspects of it I'm in the dark on, so I can venture a guess.
Due to some of the ways Shueisha wants to move forward in a positive way that legitimizes fans, they're trying to establish some ground rules before moving forward.
This is a classic Japanese way of doing things. Intimating without making a statement. It is a poor way of applying their culture to the world.
At the same time, they're also between a rock and a hard place because once they make an official statement, areas they previously held as grey or looked away from, require them to take action. I cannot stress how much this applies to almost every aspect of Japanese business society. I'm not saying it's good/acceptable. I'm saying it's reality. I've personally experienced it in my work outside Shueisha. Businesses are willing to turn a blind eye to grey areas until something occurs that forces them to address it. Once they address it, they hardline. It. Sucks.
I think that what I can't discuss, is what's forcing them to 'address it'. But, even for Japan, this is a pretty weak acknowledgement of the issue. They could have gone a lot harder, but that's why I strongly suspect this is a message. It's just a very poorly addressed and awkward message made all the more confusing and difficult to accept because no one has any idea of what they want to do in the future (spoiler: has nothing to do with 'stamping out piracy' etc)
Not saying how you should/shouldn't feel, just trying to help interpret what I think happened.