Which "Power Available" graph is more correct?
Power is work getting done over a period of time.
Work is force multiplied by distance.
So when you are sitting at the beginning of the runway, at full throttle and brakes on, while thrust available is very high, power available is 0, because no “work” is getting done.
Edit- basically you are applying a lot of force, or using a lot of thrust, but since distance traveled is 0, no work was actually done.
Which is why the power available is indeed 0 at a velocity of 0, and increasing rapidly.
Note- the second graph is exactly the same as the first, only it is showing the curve beginning at some point after the stall speed.