> In addition, to evaluate potential bias because of unmeasured systematic differences between consumers and nonconsumers, we conducted a sensitivity analysis excluding vegans. Vegans comprised a substantial portion of the zero egg consumption group, which could disproportionately influence this group, and they often differ in other lifestyle or health-related characteristics.

So they eliminated vegans from the sensitivity analysis despite them comprising a substantial portion of the no-egg group.

If the analysis doesn’t hold with vegans included, it’s probably saying a lot about dairy rather than eggs.