It’s putting the cart before the horse. The golden age started because of a national embracing of Christian values (Catholicism is a messed up brand of Christianity but still, there’s biblical root).

The expulsion as it states was part of them trying to get Jews to convert to Catholicism.

Nations that embrace biblical truth tend to be happier, better off in many ways, free-er, etc. Because even atheists adhering to the principles of wisdom will benefit in spite of their lack of belief.

Which is more likely?

A) Jews get kicked out so their country starts doing well immediately

B) they kick out Jews because a surge of religious devotion and that same religious devotion benefits them just as it did America and many other European nations before they apostasised?

Option A still leaves a a question of what forward steps would lead to a golden age, whereas option B answers both the driving force behind the golden age and explains why they’re kicking the Jews out.