This could work if the conclusion were about improving overall company morale or something else related to the entire company, but the conclusion here is just about pleasing the subset of cafeteria customers.

This doesn’t give us reason to suspect the mushroom dish will stop performing well in the long term.

And wondering whether any ingredients overlap is kinda wild. Butter, flour, water, eggs – all these go in tons of very different dishes.

This proposes an alternative cause for the mushroom dish’s high performance on days 1 and 2 that won’t persist in the long term. People like new stuff, so they pick the new thing at first, but in a month or two the mushroom dish will lose its novelty.

The argument already controls for side dishes. Whatever other foods are offered besides main dishes, the mushroom dish still performed better than its competitors.

The argument already controls for other meals. Regardless of what, if anything, is being served for breakfast and dinner, the mushroom dish still performed better than its competitors during lunch.