Because the biomechanics of running would change a lot in the moon environment, any answer is a preliminary one, pending actual experimentation on the moon. :D
That said, the indoor case can still be calculated pretty accurately due to the fact air resistance is by far the most important factor. This paper calculated that Usain Bolt was using 92.5% of his effort to overcome drag when he was at his top speed of 12.2 m/s, or 44 km/h. Since the force required to overcome drag increases with the cube of velocity, even in 0.5 atmospheres he could only go slightly faster.
The case in a vacuum depends entirely on how much of the savings on vertical force can be applied as horizontal force, and how well a runner can manage the increased speed. The graph in the question suggests that if all the saved vertical effort could be applied horizontally, that force would increase by a factor of 3.3. Bolt would then be able to run at 40 m/s, or 144 km/h. You may already see the problem, but before getting into that, let us note that since there is no air resistance, if there wasn't that other problem, he could run even faster. Nothing is slowing his forward momentum, and he only needs to apply a small fraction of his force to overcome gravity, so as long as he could continue to apply the remaining force against the ground, he could continue to accelerate.
But he has to be able to swing his leg faster than the ground is already passing under him in order to increase his speed. The force that represents the difference between how fast he can swing his leg, and how fast he is already moving, would be applied as acceleration.
I took a little video of me swinging my leg as fast as i could, just above the ground, above a measuring tape. It took very close to two frames of the video for my foot to cover 50 cm. That is a speed of 15 m/s, 54 km/h. My leg measures 88 cm. I can't find a figure for Bolt's legs, but he is 13 inches taller than me and has a much longer leg relative to the length of his torso. I'm going to estimate his leg is 108 cm. If he can also swing his leg through the air at my top speed, he would be moving it at 66 km/h. He can probably do it faster, but maybe not by much since this is not a simple question of strength. I'll call it 70 km/h.
If he is moving forward faster than he can move his legs, he is going to fall. But moving at the top speed his legs can move is only going to occupy about 60 % of his strength. It seems reasonable to think that he could do that despite the biomechanical problems. For one thing, he could slightly increase the force he is applying vertically so that he is hopping high enough that he has time to position himself exactly how he wants for the next push against the ground. Also, one could surely maintain a pace that only requires 60 % of your strength for a long time. You could probably run a whole marathon at your top speed.
His main problem would be learning not to overshoot the speed his legs can handle, and having adequate protection for when he does. Falling at over 70 km/h is no fun.
(Notes - This would be on the hard-packed lunar soil 10 to 15 cm under the surface - a track would have to be prepared. It is assumed that through the use of adequate cleats the lack of traction due to low weight could be overcome. Matters not covered: how to turn.)