T'was not meant to be a serious suggestion, but if we're going to discuss potential ramifications of the shit sandwich motive...

Obviously Silas would get the worst of it, that we know. But what of the rest?

Assuming that the shitty sandwiches are tailored to each student for maximum shittiness, I imagine those used to eating unappetizing foodstuffs would be able to take it. The students picky enough to starve themselves would have to eat eventually, as they'd be dead [i]anyway[/i], so perhaps the prospect, combined with horrible thinking due to starvation might cause a death?