what i wrote is that being vegan has not had the effect you are proposing it would. you are making up a scenario where it might work and asking why i don't think it would work in that scenario.
Both "ethics" and "morals" fundamentally deal with questions of right and wrong, good and bad, and how we ought to behave. In many philosophical and everyday contexts, the terms are used interchangeably without causing confusion. Ultimately, trying to differentiate veganism as purely "ethical" rather than "moral" is likely a semantic game rather than a meaningful philosophical distinction.
You can confidently assert that there's no significant difference between ethics and morals in this context.
sophistry is shitty. they had no interest in a genuine discussion or learning anything: they're just trying to show how right they are, regardless of the facts