Time is up, and the ball has been made dead, so 5.7 applies.
The penalty has been taken under 5.7.b
The ball has not been kicked into touch, so 5.7.c does not apply.
So I see no reason not to end the half.
As I understand it, the kicker can retreat any distance from the mark, and can kick in any direction. So they could retreat to their own dead ball line and kick the ball over that. Which makes the whole, you have to be able to kick the ball out, pretty pointless. The side awarded a penalty after time is up, should simply have the option of ending the half.