That is an interesting idea...the caster can see the sky in the zone he wants to send the creature to, just not the ground, and this creature will be in the sky. Currently however the answer is no, he would not be able to teleport unless he had los to the zone, which as currently defined would be blocked by a wall.
I agree with this decision and think that thematically teleports must inherently place things at ground level. After the teleport the flier takes back to the air immediately. Otherwise, if you could teleport things into the air, you could use it to insta-kill stuff.