The company that provided the data, Surgisphere, might have been trying to raise their profile by getting a big publication. They're a bit shady.

https://blogs.sciencemag.org/pipeline/archives/2020/06/02/su...

To prop up a competing medication.

Increased sales of a competing medication, like Remdesivir.

There a huge battle going on between hydroxychloroquine (the Republican therapy of choice when combined with a zinc supplement) and remdesivir (the antiviral drug by Gilead that's preferred by anti-Trump liberals).

To answer your question, there can be an economic interest in claiming a competitor treatment (which is generic and manufactured cheaply) doesn't work.