In fact the paper explicitly discusses (p. 14-16) potential synergistic effects between zinc and hydroxychloroquine, and provides references to another study suggesting the same. Care to comment, Doctor?
If we assume that the majority of "non HCQ" patients were of group (e), young people, then their rate of mortality in this paper would be at least an order of magnitude higher than that of any previous paper, therefor I would expect group (d), old people with complications, to be more likely to have higher representation in their "non HCQ" group.
I didn't conduct this study so I don't have access to the raw data not provided in the paper.