IIRC, after the Moors had been expelled from Spain the piracy skyrocketed thanks to the new arrivals who had a big axe to grind.
Obviously they did not know that, as the austrians did not know what would happen if they attacked Serbia or the British did not know what would happen if they taxed the tea in their american colonies...
Now, the Moors had been ordered to convert or to leave Spain in 1501, more than a decade before Ottoman conquest of Algeria (1515) and few decades before conquest of Tunisia so the 5th column excuse is hardly believable (Moriscos is a different story of a later period) and it hardly made practical sense to fight the piracy by forcing the angry and looted people to go into the piracy nests.
But, in fact, they were not expelled in 1501. The Law of February 14th 1501 ordered them to convert or leave the kingdom, but there was another law on February 17th 1501 that prevented them from leaving the kingdom. On July 1501 the moorish population from the rest of Castille was forbidden to enter the former kingdom of Granada.
The attacks of the berberian pirates were already reported in the XIV century and in 1505 Elche, Alicante and Malaga were attacked by pirates.
The Ottoman threat (at the time of F&I a pure fiction) would not also explain the fact that the Jews had been treated the same way as the Moors: convert or be looted and expelled.
Obviously the jewish question was really different, here Ferdinand and Isabella probably "corrected" what could be perceived as an annomally respect the rest of Europe were similar laws were promulgated in the previous centuries. The reason would be more religious.
Taking into an account that most of them lived in the Catholic kingdoms of Spain for centuries (and quite a few being very successful) the 5th column story would not make any sense and yet the pattern was the same and continued to be the same: 1st force to convert or to leave and then deal with those who converted.
It DID make sense for the populations in the coast. It was very common that neighbours of islamic faith cooperated with bebers to raid coastal populations and capture slaves. That is why all the coastal populations in the mediterranean coast were built far from the coast!
As an idle thought, in both cases the royal treasury was getting a lion share of a property so this was a scenario where ideology (religion) and “materialism” (getting money) had been going together as horse and carriage. Nothing unique: look at the standard medieval practices toward the Jews in, say, France (in the case of Phillip the Fair it would be Jews and quite Catholic Templars and, IIRC, he died while planning to do the same to his Italian bankers).
But they were allowed to carry their properties and no confiscation was made. They could not take gold or silver, but they could carry anythig else and bills of exchange. Probably their christian neighbours took advantage, but there was no confiscation by the crown.
As for Las Novas de Tolosa, it is probably relevant to mention that while Alfonso VIII had a Jewish mistress, she and all her family had been killed by the fanatics after Alfonso was defeated at Alarcos (or at least so the legend goes). Anyway, by the time of F&I Las Novas de Tolosa was an ancient history and victorious monarchs faced a problem: their victorious pure-bred Christian subjects had been getting nothing but a spiritual reward while there were plenty of easily recognizable “others” who were much better off.... Guess, what was the obvious solution.
There was no sacking, no confiscation,... not even pure-bred Christian subjects: people that converted to catholicism form judaism were allowed to stay. In fact, most of them converted.
Of course, Phillip II (who was decades later) was a special case in the terms of sincerity but the treatment of his Protestant subjects hardly could be explained by the Ottoman threat to the Netherlands.
I thought we were talking about the end of the Reconquista... Other day we may talk about this (spoiler: there was no spanish Inquisition in the Netherlands and the main issue was loyalty to the crown, not religion).