It would be really helpful if you would cite the specific article. Magnesium stearate is used in many supplements and pharmaceuticals as well as foods.
I cannot find scientific evidence that it is harmful to humans in the quantities that would be consumed in supplements and medications. It does appearmthat those who take too much may experience a laxative effect.
Here is what was reported after evaluating the studies of massive doses in mice and hamster lung cells: " Many magnesium-containing food additives have been evaluated individually, but not collectively, for laxative effects. Based on the recent dietary exposure assessment to magnesium stearate and concern that use of magnesium salts in many food additives may result in cumulative exposure that could lead to a laxative effect, JECFA reiterated its earlier recommendation [35] that total dietary exposure to magnesium from food additives and other sources in the diet be assessed [15]. Although effects of cumulative exposure to magnesium via food additives should be evaluated, the studies reported here indicate a lack of genotoxic risk posed specifically by magnesium stearate consumed at current estimated dietary exposures." (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5655391/)
The articles I found citing possible harm seem to be published by supplement distributors, some of whom (like NOW) actually use them in their products.

So, as with all things, it appears caution and moderation are a good thing. None of the supplements in my cupboard contain titanium dioxide, so I did not research it.
Sue