Why hunting for life in Martian water will be a tricky task (nature.com)

"Carl Sagan famously mused that if life is ever found on the fourth rock from the sun, “Mars then belongs to the Martians, even if the Martians are only microbes.” In this view the planet would become a sacrosanct sanctuary, forever off-limits to encroaching humans."

What sort of broken understanding of ownership must one have in order to posit the idea of microbes owning anything?