Also, the nice thing about the peer-reviewed literature is that it is published. Anybody can read it and point out inherent flaws. Indeed, if you can identify a serious problem in a paper, and back your discovery with facts, you'll have no problem getting your counter-point published. There are literally tens of thousands of examples of precisely this happening available for your perusal, in the peer-reviewed literature!
It's not like major polluters, such as oil companies, don't have the bankroll to fund scientists to demonstrate that the claims about climate change are false. Their continued silence is like the dog that didn't bark in Conan-Doyle's "Silver Blaze"
I am unable to judge the impact of that kind of obstruction on their actual scientific argument. It could well be that the significance of the so called climategate is way overblown.
But it's definately not confidence inspiring behaviour by scientists who have so much to gain from a global warming panic.
As for preventing critical review, I am unaware of any such activity. Do you have a citation?
One thing I consider preventing critical review is the lies about the original temperature readings that were thrown away in the 80s. The only plausible reason for lying about that is to make it easier for them to defend their own conclusions and make it more difficult for critics to check for errors.
But as I said many times before, I'm not one of those who claim to have found some kind of unambiguous smoking gun in those emails or code comments. Not about the science proper anyway. It seems to me that there is an attempt to hide something but I'm not quite sure what that is and whether it's of major consequence to the science itself.