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In many cultures it’s taboo to openly criticize a guest or make him feel uncomfortable.  The scenario described by the OP seems unusual
It may be rude for an outsider to violate their food rules, but it’s even more rude for them to publicly shame an outsider who didn’t know better. >

Agreed. If I made a faux pas, politely inform me of what the issue is and why it's an issue and I'll do my best to avoid it in the future. Jumping down someone's throat because they broke a rule they didn't even know existed is absurd, and is a straight up violation of any cultural rules on hospitality I can think of.