[Harmless Teddy Bear]

Bacteria and other organisms from the body could contaminate the Martian surface.

And the down side is?

If we are there so are our little fellow travelers.

If we are going to stay there so are they.

And life finds a way.

So learn to deal with it.

[Jewbacca]

You have to understand that liberals hate humans first and life itself second.

If you understand how much they despise humankind, it makes sense they hate all traces of us, including our flora and fauna.

Hence the worry.

It actually explains most all their thinking and behavior.