In Taiwan, asking if the pork is local when ordering at a restaurant is generally not considered rude. Taiwanese cuisine often emphasizes the use of fresh and local ingredients, and many people appreciate customers who show an interest in where their food comes from.
Asking about the origin of the pork can demonstrate that you care about the food's quality and the restaurant's commitment to using local products. Additionally, it can lead to a more informative and engaging dining experience, as the staff might be happy to share information about their ingredients and sourcing practices.
However, as with any question, the way you ask it matters. Be polite and respectful when inquiring about the pork's origin, and avoid sounding accusatory or suspicious. A simple and friendly question like, "Is the pork locally sourced?" should be well-received in most cases.
Just keep in mind that cultural norms can vary, and while this question is generally acceptable in Taiwan, it might not be the case in every region or country. Always be mindful of the local customs and context when asking questions about food or anything else in a foreign place.