Well, like I stated, contextually, it checks out. Do people need to show another tier 7 feat afterward for a feat to be valid? Why can't a feat be valid by itself? When people say "outlier," they think of a bunch of data points with one sticking way out. But what we are talking about here is linear progression. They gradually grow stronger and stronger and when graphed, this would be the highest and most current feat. That isn't an outlier, that graph would show exponential growth. I also think black holes are a case-by-case thing. Attacks named "Black Hole Attack" or "Hole that is Black" and they're just some weird sphere being thrown at an opponent, I'd chalk that up to a name fallacy, but when they take the time to go through and explain how a black hole is made and show it happen, well that's clear what the author is trying to depict and convey.
This is what people think of when an outlier is called. The difference is, where the outlier occurred, the progression afterward shows another pattern. In this case, There isn't any linear progression afterwards to call it an outlier. Its called growth in this instance.