"The links Barry gave to the NASA scientists responding to Zubrin's views in the Planetary Report are some.
A charge that has been leveled at Barry is that the decision on planetary protection should be left to those scientists with the requisite training in biology."
I don't recall this charge, what I do remember is that Barry made various statements which led a couple people to the conclusion that he was clueless on the subject of biology- basic biology. I also remember some complains of Barry giving references regarding biology in which the people had no formal training as biologist. In other words if you choice to cite an expert, the expert should be an expert in the subject.

"The scientists who responded critically to Zubrin's remarks are scientists with that training."

That's fine, but it doesn't neccessarily prove anything (other than Zubrin lacks a good understanding of biology and tends to talk like some expert in areas in which he at best has superfical understanding or worse chooses to ignore relevant problems becauses it isn't convenient for him).

"One scientist in particular probably has the most extensive knowledge both of extremophiles and the conditions on Mars, Kenneth Nealson. In fact he chaired the committee that wrote the prior National Academy of Sciences report on Mars Sample Return. It is interesting that Nealson now proposes further in situ life testing before samples are returned from Mars."

Why is this interesting?

<snip>
"The committee proposed specific guidelines for release of samples from the facility. If found to contain no organic matter or other evidence of life, they could be released without sterilization.
"If the samples contain possible evidence of life, which is the most likely case, portions that have been sterilized by heat or gamma radiation could be certified for release and study elsewhere.
"If the samples are found to contain unmistakable evidence of life, they should not be released at all until an expert panel of biologists is convened to rethink the situation; the establishment of a research facility dedicated to their study, far more extensive than the quarantine facility, will probably be justified."

"It is interesting here they are saying the most likely case is that there will be found "possible evidence of life," which I take to mean existence of at least organics in the sample. If this is what they mean then that would be a turnaround from the previous viewpoint about returned samples from Mars. "

I don't get your point- the main purpose of a sample return is to look for evidence of life.

"Since such samples would be returned form the top few centimeters of the Martian surface this appears to be saying they expect to find the organics there."

That or fossils or anything related some kind of life process.