True. But that also means to say certain opinions are flawed because of bias is kind of pointless, isn't it?

what some protester writes on a blog (because that wouldn't be biased at all...)

At least it's first-hand bias. Those people put their lives on the line, literally, so while I agree one shouldn't just take a handful opinions and believe them, I think you can't just easily dismiss them for being protesters, either. It takes a lot of material to come even to a tentative conclusion, but it's possible. Then you'll still be biased but I guess that's the price of being human.