colwyn -
It is not a double standard. I call people out over statements they make on the topic at hand which are wrong.
Thus, when evaluating statement A on topic X, I take into account the person's reliability on topic X as determined by whether statements B,C,... on the same topic have been accurate.
What I don't do is consider:
Have they previously been upright moral people, lied to their wives/husbands, been imprisoned, etc.
Have their statements on other topics far from that relevant been accurate
Have they skills/qualifications etc of any kind.
Have they reasons to lie/psychology that makes this likely/etc
These other things are all meta-evidence, and very weak when compared with the details from the topic at hand.
You might say I should consider each statement on the topic at hand out of any context and ignore the fact that a given person (for example) has regularly made technical statements that are false. I have sympathy with that approach but think its a bit silly when some actors (e.g. Rossi) regularly make technical statements that are self-contradictory. To ignore this when evaluating their other technical statements seems unwise.
In the case of Mats - his technical reporting is a good read and appears unbiassed, but if you look at the details you see he holds up two sides of a scientific issue with selected advocates without going in detail into how the issue resolves. You can for example do this with the AGW debate obtaining an apparent stalemate between those who hold the heavily reviewed and quite uncertain (but with well quantified uncertainty) IPCC position, or those who think baldly that this is wrong and highly biassed. In reality when you go through the science, in detail, the contrarian points made are nothing like as strong as they seem when summarised. thus a journalist can easily seem "unbiassed' by selectinmg both contrarian and mainstream viewpoints, giving each equal weight, when one is in fcat much more factually based than the other. I've gone rather OT in this paragraph.