The usage of temperature to describe space really throws off laypeople that aren’t used to temperature in a scientific context. Temperature is an average measure of the particles in a system. Since there aren’t many particles, space is “cold”. But it’s not. It’s not cold. If you took off a spacesuit in space and “survived” you would overheat from absorbing heat from the sun OR from your body overheating since you wouldn’t be able to shed the heat. You wouldn’t freeze. There’s hardly any particles to transfer energy between bodies.

In this case, either the particles are traveling faster than in our solar system, or there’s more of them. Even if there’s more of them, there’s still not many, it’s a vacuum. So the “temperature” just reflects the average of the particles.

It’s like being in a bowling alley. The “temperature” is the speed and collisions of the balls. But the people there aren’t ever going to be hit by a ball. So if you bring stronger people to the bowling alley and they throw the balls much harder you can “raise the temperature” without affecting a single person.