Big difference between "some organisms hitched a ride and didn't immediately die" and "we created a self sustaining ecosystem that will spread across a wide are

Big difference between "some organisms hitched a ride and didn't immediately die" and "we created a self sustaining ecosystem that will spread across a wide area in a human relevant period of time." The venn diagram of organisms that can survive on mars, those that can use martian conditions to produce all the energy and nutrients they need to survive long term, and those that would be likely to contaminate a spacecraft likely doesn't have a lot of overlap.