If you stayed, you had to be converted or die.
If you went, you could stay Jewish.
It’s that simple.
Not simple logic at all since from the moment of the decree, it would be hard to take seriously any conversion to Christianity. So its not a program for converts. The Decree itself never spells out you had to be converted. No word conversion exists, no exhortation to embrace Catholicism.
However, I’d give you that there would possibly be some who would lie about their Jewish Faith, and then be baptized. But that isn’t compulsion to join a faith, it is someone who would desire their property over their religion. At the time, even the Jewish Community would have abandoned such an individual.
It would be worth looking into the cases of inquisitions. It should be noted however, that during the entire life of the Spanish Inquisition, Every kingdom of the world engaged in persecution of religious minorities.
But looking into Spanish Aragon, for example, 100 years of cases of Inquisition from 1540-1640, found about 942 accusations of being a Marrano, which was about 3.6% of total cases involving false-conversions.