It's poor science at best, if you can't control variables then the whole thing is next to useless, which happens a lot these days. At the end you have correlations, not causations
You'll always have to augment statistical associations with further knowledge of the world, so you can get to causes.
Bogus science can move us forward, but also backwards.
The response to a paper ought not be, “This paper is bogus because they didn’t control for all variables.”. If the paper is bogus then give reasons for why this is the case. Was the statistical analysis wrong? Are there reasons why this can’t be true? Is this new information worthy of further investigation?
It’s sloppy thinking to say it’s a bad paper without having studied the issue and the data.
Retrospective studies are fairly rife with poor science. They are heavily limited by the data collected and can be easily manipulated by changing different controlling factors. While I wouldn't describe the paper itself as bogus. The title certainly takes a lot of liberties.