A small (effectively zero) positive correlation was found between the amount of time a student says they spent on homework in elementary and achievement, but a slight negative (effectively zero) correlation was found when looking at the time parents reported students spending on it.
These measures don't show a causal relationship: "good students" are more likely to do homework. "poor students" are more likely to take a lot of time to complete the same amount of homework.
Elementary student reports of time spent on homework are not reliable. Parent reports are even worse.
The only causal evidence of a benefit in assigning homework in elementary comes from two short-term intervention studies: whether giving a homework take-home worksheet about vocabulary improves performance on the next vocabulary test (it seems so, very slightly). The longest term observational studies show a negative effect.
You are citing research that apparently is stating the obvious, namely that good students are faster at completing homework than poor students. Not sure how that supports the statement that homework is harmful for either group.
Skimming the lit review you linked, homework appears to have a moderate positive effect on the immediate measures of achievement, e.g. grades. Though the effects of lifelong habit of completing one's homework are more interesting than short term grade improvements, and a quick skim of the 60 page lit review you quoted doesn't seem to attempt to quantify this effect.
Food for thought: attempts to scientize every aspect of life, even if the measures used are obviously limited and shortsighted, is perhaps not a good way to steer an entire society forward.
AS SAID: I deliberately sent you the most pro-homework review. Despite being confounded in almost all of the component studies (being based on reported homework completion times rather than amount of homework assigned), no real benefit was shown in elementary.