I recently became aware of possible legal consequences. E.g., listed at Jeffrey Beall - Wikipedia. Some other background at GitHub - stop-predatory-journals/stop-predatory-journals.github.io: A listing of predatory academic journals and publishers..
Not sure if we should keep that feature. It also does not work great as there are many false positives: Integrate check-bib-for-predatory · Issue #348 · koppor/jabref · GitHub
Maybe, we should just offer the user to maintain a list of allowed and denied publishers?