"starts with a premisis and then works to a conclusion"

The extreme religious right mantra.

Actually the scientist you mention was stating that if there were life in the Mars samples brought back to Earth we probably killed it by using water in testing.

You can use your same logic to teach that the bogey man might exist also. Or ghosts under your bed at night. Tooth fairy? Easter Bunny? Santa Claus? Or whatever you wish to make up but it still won't be so. This logic is exactly why we need to strongly teach our next generation to not think like their misguided parents. At some point people need to use their minds. If you can prove that the majority of scientists are wrong in their conclusions then you may have something. Until then that's what we have to go with and teaching anything else is simply "starts with a premisis and then works to a conclusion"