@BloodySorcerer
I would guess it depends on how the fight starts. If the space user surprise attacks the light user, the light user would be defeated/killed by what you have said instantly since he would be caught unawares. However, the opposite is true. The last type of fight would be something like a duel where both opponents start at the same time, I would argue the light user would win. Let's say that in the duel the space user is able to summon his constantly expanding space, trapping the light user. This is still imo in favour of the light user since they are moving at the speed of light.
TL;DR: The light user uses less energy to deal with the space user than the space user does to deal with the light user. Hence, all the light user has to do is to win a battle of attrition.
Wall of text and math incoming
The light user is 100% doomed if he is trapped within the event horizon, as even light cannot escape. However, the forming of a black hole is not instant, it still takes less than second. Let's say the black hole fully forms its event horizon in 0.5 seconds. In 0.4 seconds, the light user is already 120 million km away, safe from the event horizon. I do not believe that the space user can summon a black hole that will be fully formed with its radius exceeding what light can travel in 0.4 seconds. Remember, he is already maintaining a constantly expanding space just to contain the light user. Hence, the light user can simply wait until the space user is exhausted.
Some context for my next part:
Light is made up of photons. Photons have no mass, and objects with mass cannot travel at the speed of light. So for the light user to travel at the speed of c (light), I would assume his power also makes him have no mass when he is at the speed of light, thus all of the particles that make up his body turn into photons (or at least some particle with no mass that move at speed c).
E = energy (joules)
h = planck's constant
c = speed of light = 3x10^8
f = frequency
λ = wavelength
Ok so, to support my claim of the light user using less energy, we will calculate the energy of a photon with wavelength 550nm (Within the visible light spectrum and let's make the colour white because it's cool).
We solve for frequency:
c = f/λ
f = c/λ
f = 5.45x10^12
Now, we can solve for the energy of one photon:
E = h x f
E = 3.62x10^-21 J
But, we are assuming
all of his particles turn into massles particles all moving at speed c. Quick google search shows the average human body has 7x10^27 particles, so we times that with energy per photon and we get:
Total E used = 2.53x10^7 J per second of time the light user is at the speed of c. This is not counting all other energy used by the human body but thats a rounding error compared to the energy needed to move at speed c.
Now, the energy consumption of the space user. First off, I don't know how to calculate the energy usage of his constantly expanding space, but since it can contain the light user, it is moving at or faster than speed of c. So, I'll decide it uses the same amount of energy per second as the light user.
Let's say that the space user can make something the size and energy output of our sun into a black hole. He can instantly collapse space and make a black hole there (no supernova, that's crazy) while injecting one second of the energy of our sun's last breath before it instantly collapses. Our sun generates 3.8x10^26 Joules of energy per second. That's how much our space user needs to put into the black hole's forming. After that, the diameter of the event horizon around the singularity is only around 5928 metres. It only takes light to cross 5928 metres in 19 micro seconds (19x10^6 seconds), so our opponent would be long gone and would not be caught in its event horizon.
My last paragraph regarding the energy use of making a black hole is most likely incorrect, as I have not studied black holes in much depth at all. However, I believe my point still stands; a man moving around at the speed of light is less intensive than a man maintaining a constantly expanding space at the speed of c and making black holes). If anyone has read this far, thank you for reading! This took me a bit to write, but I guess I enjoy trying to apply what I've learnt in school to something I find interesting or worth being discussed.