Possibly. Their figures are likely to be bollocks though, which the researchers I would imagine know. If you were writing a paper about bias, I can see why you'd include them, but not if you are using their figures without comment and are therefore legitimising them.
I don’t think there are a glut of relevant studies (which may explain their inclusion) and it’s possible their methodology has checked-out … but fair point.
Possibly. Their figures are likely to be bollocks though, which the researchers I would imagine know. If you were writing a paper about bias, I can see why you'd include them, but not if you are using their figures without comment and are therefore legitimising them.