Is not possible that he can get an English passport after 5 years in the country? Meaning he will be classed as English (even though he plays for Argentina. Dual nationality) Meaning he will no longer take up a foreign player slot in our squad. Freeing up a position for another foreign player if we want one.'Home Grown' means a player must have been on the books of a club affiliated with the Football Association for at least three years before the age of 21 (a few refinements but that's the basic test)
So players from overseas (or even those from clubs affiliated to Welsh, Scottish or Irish FA's) need to join Spurs before they are 18 to become home grown. Foyth did not !
(All knowledge based on football manager games)