Actually, you need to actually read and consider what the article says. Jupiter and Saturn (and especially Titan) are methane factories, but the methane is created by chemical interactions in the atmospheres of those planets or was an original constituent of their atmospheres.

What the scientists are saying is that methane is not generated from chemical interactions in the Martian atmosphere - the ingredients and the climatic requirements for the generation of methane are completely absent. That leaves two sources for the methane: Volcanism, of which there is no current sign, or some primitive form of life which inhales CO or CO2 and releases methane as part of its respiration cycle.

This is significant if the second option is the one which is true, which must, by deduction, be the case if there is no volcanism on Mars.

Unless, of course, there is some third way of generating methane which the scientists don't know about, but.