Just giving my perspective as an American-Israeli: In the Jewish world in general, but in Israel in particular, there's controversy over who counts as Jewish. The Israeli government looking into the case but the Jerusalem Post not saying anything about his religious background could indicate that they're not sure how to classify him and don't want to wade into dangerous waters. This would apply if, for instance, he had a Jewish father and not a Jewish mother, or if he had converted in a way that the most stringent authorities might not recognize.
Over the years, I've also met a number of people from places like Spain and Italy who had good reason to believe their family had Jewish ancestry but had converted during the Inquisition. There's a small but real movement among people in this situation to return to their Jewish roots. So also possible that Prof Loueiro was someone with likely Jewish ancestry who had either formally converted or was exploring that aspect of his past.
