Sure. Generally, it is a marker for life as we see it being produced by living organisms on Earth (e.g. Algae) and it also should vanish quickly from atmospheres if it is not replenished.

However, as you correctly put it, there may always be a non-biological explanation as well for any of these markers, which we might not know as of yet. So far as I know, DMS has no non-biological explanation and is seen as a biological marker still.

Alas, the possibility of it being proven non-biological or even (as happend here) not a real detection makes it even more important to get more data and be very careful about the statements made from it than as otherwise those statements and/or connected papers have to be corrected/retracted. And if these then reach the public (and why wouldn't they with the possibility of alien life) then this could diminish the trust in science if it turns out to be wrong.

Edit: I had a look and as you stated for DMS there may indeed be abiotic ways to produce it (scientific works from this year). They found it in comets and could reproduce it in labs as well.

My main point of the original comment was to add that the detection (paper) itself was flawed. Regardless of DMS being a sign of life.