RTFP (read the fucking paper).
While I'm sure you're much more of an expert then the researches who actually conducted this study, they do specify that the strains present are from livestock based on genetic testing. The introduction in the paper specifies why those strains are livestock-associated and what that means.
Here's the link, since you seem to have missed it even though the link is the first two words of the summary:
So it seems to me that responsible researchers would go a bit farther before reporting: Like by doing genetic testing on the strains of bug in the various workers and the livestock, and running models on the results to try to identfy whether the bugs are from the herd or the workers.
So it seems to me that a responsible commenter would go a bit farther before accusing the researchers of not thinking of something that they in fact did think of and went to great effort to do genetic testing on hundreds of samples for. But I guess you couldn't be bothered to at least RTFA (read the fucking abstract).
I'm actually pretty impressed that the summary linked to the actual paper and not just the journalist article. I'm not impressed that you didn't at least read the abstract before commenting.