I know what fingerprinting is, thank you.
However the claim was that "This [the fact that an app is blocking access based on another app being installed] should tell you that the app is looking at everything on your phone"
It doesn't. The only thing we can conclude from this isolated incident is that they are checking against a blacklist of applications. We can conclude nothing more from it in isolation. Nothing. You're free to speculate, and say something like "this could suggest that...", but stating it as a fact is like seeing the sun in the morning and concluding that it's not going to rain all week.
Also, fingerprinting isn't even close to "looking qt everything on your phone"