The traits that allow something to survive extended periods in space don't automatically grant it the traits that would allow it to thrive on Earth above all else.
Look at Earth's extremophiles, the bacteria that can survive near thermal vents on the ocean floor, extended trips in space/vacuum, intense radiation, sub-zero temps, etc, there's no evidence that they're taking over the non-extreme locations. Even if they do survive outside their "home" environment, that doesn't automatically make them the top dog that will edge out everything else.
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The traits that allow something to survive extended periods in space don't automatically grant it the traits that would allow it to thrive on Earth above all else.
Look at Earth's extremophiles, the bacteria that can survive near thermal vents on the ocean floor, extended trips in space/vacuum, intense radiation, sub-zero temps, etc, there's no evidence that they're taking over the non-extreme locations. Even if they do survive outside their "home" environment, that doesn't automatically make them the top dog that will edge out everything else.