For if he wants he can bend down and eat - דאי בעי גחין ואכיל
According to רש"י we require that one’s hand rises more than three טפחים from the ground to be קונה. According to תוספות if the item is in one’s hand or mouth he is קונה regardless whether it is less than three טפחים. The case of גחין is where it was on a rod and he never took it with his hand, but rather placed his mouth over the rod.
Let us say, picking up is necessary for carrying out - נימא הגבהה צורך הוצאה היא
According to the ר"ת who does not require ג' טפחים for קנין (while עקירה requires ג' טפחים), we need to say that the ruling of גונב כיס is (even) where he picked it up from a rod which was ג' טפחים aboveground.