It's getting rapidly obvious just who this guy is. Just the way Tidus reacts to him, and those few words - his old man - are enough, considering that's always how Tidus refered to the guy whenever he spoke of him before. It's obviously fake, just an illusion, but a very mouthy one. An illusion of Tidus's dad, actually capable of speaking to him, and most likely even acting the way Tidus's dad did during life, if his friend's reactions to it are any indication.

That thought distracts him from the boyfriend comment - thankfully, since Inigo doesn't need that public embarrassment, even though he can feel his cheeks growing faintly pink - and from the fact that hello, how come Tidus has a hot dad?! That's not how dads are supposed to look?

Instead Inigo tries to take this situation more seriously, glancing between Tidus and the illusionary man.

"You don't sound so sure of that," Inigo ends up saying to Tidus, figuring that's going to do more than engaging the illusion first. "And I'm not going to leave you behind here."

Not in this situation.