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In the past, the Arts Canteen had separately marked tray clearance points, like this contemporary example from Business. The crude dichotomy between Muslim and Non-Muslim was problematic (as opposed to 'Halal' vs 'Non-Halal', which was less problematic); Non-Muslims food was defined not by what it was, but by what it was not. This essentialism resulted in the condensation of a virtually unlimited spectrum of culinary possibilities into a single, bland term. Non-Muslim culinary identity was constructed in opposition to Muslim food, forever trapping it into this restricted dialectic.
I'm not sure that the current situation is an improvement. Now, food is either Muslim or Nothing; instead of an empty signifier, we have no signifier at all. Furthermore, the labelling has been simplified, which opens up new layers of complexity; "Utensils from Muslim Food Stalls only" is less problematic than the simplistic labelling of "Muslim". For example, one implication might be that only Muslims can eat 'Muslim' food.
As for the lack of a signifier for utensils from Non-Muslim stalls, there are at least 2 possible interpretations. One is that Non-Muslim foods are free from this crude essentialist dichotomy and are free to reclaim their individual, fragmented identities and subjective experiences. Another is that they now unimportant and have no significance - they do not matter.
Which interpretation one adopts then, like with much of the Arts and Social Sciences, depends on one's ideological leanings.