Of course a researcher is never sure something is 100% ruled out. That’s part of how academic research works.

once again, that isn't what they were reported to have said. [and researchers don't need to repeat the basic precepts of the scientific method in every paper they write, so perhaps its worthwhile to note what they were reported to say about that, rather than write it off as a generic 'noone can be 100% certain of anything'] it's a bit rich to blame someone for lacking rigor while repeatedly misrepresenting what your own article even says.

what the article actually said is

because there are some scenarios not covered by their study

and even within the subset of scenarios they did study, the article notes various caveats of the study:

Their phones were being operated by an automated program, not by actual humans, so they might not have triggered apps the same way a flesh-and-blood user would. And the phones were in a controlled environment, not wandering the world in a way that might trigger them: For the first few months of the study the phones were near students in a lab at Northeastern University and thus surrounded by ambient conversation, but the phones made so much noise, as apps were constantly being played with on them, that they were eventually moved into a closet

there's so much more research to be done on this topic, we're FAR FAR from proving it conclusively (to the standards of modern science, not some mythical scientifically impossible certainty).

presenting to the public that is a proven science, when the state of research afaict has made no such claim is muddying the waters.

which comes to your main point, you may feel as i do that the responsible collection of even witness reports should include some acknowledgement or attempted elimination of the plethora of other channels for such correlations to be realised (not withstanding ofc there's also the possibility of sheer random chance). then that's fine, i agree.

pretending its solved when its not even close merely further detracts from worthwhile discussions about non-voice surveillance channels & inferences thereof

i don't really blame you personally, the news media repeatedly fails to present the current state of research accurately. from my observation many popular headlines state "its not happening" even when the very article itself doesn't say that. its frankly dishonest or extremely lazy "journalism". and i don't mean the typical failure of popsci reporting to fully capture the finer details of a study, i mean literally the popsci headline doesn't even match their own article body.