I flat do not understand why he is taking this approach. Just normally courting her would be more effective, without talking about his 'missing pet' (whom he obviously knows is her).
There is a crapton of flat earther "science" on the internet that unfortunately leads people into believing absolute BS. You would not miss seeing an entire mountainous island at 10 km because of "perspective". The problem is clearly curvature, and is indeed soluble through altitude... which is...