Science is about testing and observation; pure speculation comes from without and is the domain of just about everything else. Saying “based on the evidence” and coming up with wild statements is not using one’s “evidence” as the basis.
You obviously wish to redefine "science" to suit your own purposes.
The fact is, you cannot have a confirmed scientific theory without first brainstorming and hypothesizing about what the answers might be.
Indeed, we can easily suppose that for every confirmed scientific theory, there are ten unconfirmed hypotheses and a hundred or a thousand brainstormed ideas.
This particular article reports on the results of new testing to determine ancient oxygen contents, leading to speculations on how that might have effected evolution of life on earth.
So, it's an interesting article, but certainly not an "article of faith".