As an interviewer, I think that certs are only useful if you take the test with a different company than you studied with. So I don’t think I’d care if you have a coursera cert, because I’d assume it just meant you finished the course that you paid for.
It’s worth noting that some coursera courses are created and maintained by actually accredited institutions, and some courses qualify as college credit with ACE accreditation. Also, many tech certifications host their courses on coursera too, like microsoft has official azure cert courses on there.
That doesn’t necessarily mean anything for any given random cert, though, because that means that the entire site is a pretty big grab bag in terms of the usefulness of their certs.
FWIW, at this point, that study would be horribly outdated. It was done in 2022, which means it probably took place in early 2022 or 2021. The models used for coding have come a long way since then, the study would essentially have to be redone on current models to see if that’s still the case.
The people’s perceptions have probably not changed, but if the code is actually insecure would need to be reassessed