If I'm envisioning the play correctly, the airborne receiver gained possession, was blocked out of the EZ, then lost possession upon contacting the ground. At that point, it's as if he was never in the EZ.
If he subsequently makes a catch of the bobbled ball, rule on it as if he was never in the EZ. If he's down outside the EZ, he's down. If he is still on his feet and can get into the EZ with possession, that would be a TD.