I'm not convinced that Pureblood Garleans would be particularly controversial in that regard. If we adhere to the logic of the player character being the exception to every rule then surely that would extent to a Pureblood Garlean as well? We already know they're not treated with outright hostility or executed simply for being a Pureblood Garlean.

A clear distinction is made between Imperial Garleans and those who are just regular Garleans or former Imperials who have since took their leave of Garlemald's forces. Given that the vast majority of Eorzea's inhabitants are also unable to read or write effectively, there's also a good chance they wouldn't even know what a Pureblood Garlean even looked like.

The Final Fantasy games also have a long track record of 'defectors' joining the protagonists, at any rate. Celes, Balthier, Cloud and others spring to mind.

Plus as Yoshi-P himself has often stated in interviews, the conflicts in-game are not presented as 'good and evil' but merely a matter of perspective. Zadnor in particular has been pretty clear about pushing that particular message, albeit as much more recent content.