That would be a very interesting idea... Would a Christian explorer have any moral objections to sailing for non-Christian court? I would think it wouldn't be too much of a problem, but of course the Iberian Peninsula wasn't anywhere near the best example of religious harmony at this point.
This is the early 1300's, right? You should know that there weren't Jewish persecutions in Castile, for example, before the assassination of Peter I and the takeover of his bastard brother Henry II in 1369. The reason was that the Jewish minority (and to a lesser extend, the Muslim) were mainly urban communities and, like the rest of the burgesses, they had supported Peter in the last civil war against Henry, who was supported by the feudal nobility. Spreeding an until then rare or unknown antisemitism among the Christian population was the way Henry used to have the population forgot his "unconventional" way to get the throne. Up to then, and not rarely after also, the population didn't have any problem to live and deal with Muslims and Jews as long as they lived in their own neigbourghoods and accepted the Christian overlordship. Same happened in the Muslim kingdoms with the exception of the brief Almohad period and the fact that, obviously, in these cases the Muslims had the political power. In short words, if there was a "tolerant" region outside of Sicily in Europe, it was the Iberian Peninsula. It's quite ironic how this tolerance ("the Spanish little sin", as it was called by the Italians) was then the main target of foreign propaganda in times of war, and how centuries later that target was the Catholic fanaticism that was born mostly to demonstrate that the Spaniards weren't worse Christians or more friends to the infidels that the rest of Europe. It's almost unbelievable how the people of today believe that Spain have been always the home of Inquisition persecutions and religious fanaticism. Kinda reminds me of the people that take the Armenian genocide and say that the Ottoman Empire was always ruled by Islamic fanatics and Turkish supremacists.
As for the "moral" objections... well, that depends of what type of "moral" followed the person itself. I'm pretty sure that Columbus would never sail under a Muslim banner, but at the same time I can provide a list of Dutch, English and Spaniards that worked for the King of Morocco in the 16th-17th centuries and didn't have any apparent problem to violate the 10 Commands of the Bible if ordered. And there is always the possibility of a man that, after being forced to leave his mother country for whatever reason, to emigrate to another nation and adopt the culture, language of religion of his new adopting country. Did you know that Rodrigo de Triana, the dude that first exclaimed "Land!" in 12 October, 1492, died as a Muslim hermit in North Africa?
Now, returning to the thread, I have a comment about the crops question related to what I said in my first paragraph. The Western Sahel trade routes drove mostly ivory, gold and slaves to Morocco, and with Tangiers (Portuguese occupied) and mostly Melilla as the Mediterranean gate of these trade. From Melilla these riches passed to Granada, were they were sold (along luxurious crops like sugarcane) to Castilian, Aragonese and Genoese merchants in exchange of meat and grain, goods that weren't enough to feed all of Granada's overpopulation. Yes, the Granadine-Castilian trade was always high, even during the own conquest of Granada, so it's not a problem in this TL to have new exotics goods from Africa and beyond passing to the Iberian Christian kingdoms from Granada. Can you figure the potential effects of, let say, Mali potatos and tomatos?
-First, they can be grown in the small mountainous kingdom of Granada, in regions where grain cannot be. Granada is less dependent of foreign exportations and less vulnerable to maritime blockades during wars. It has more chances to survive in the future.
-Second, the new crops first enter the Western Mediterranean, and the Ottomans and other eastern Mediterranean countries receive them later, from Aragonese, Italian and Algerian ships.