Well, for one, that their uneducated skim through the IPCC report found a mistake which thousands of qualified scientists had missed, one so fundamental that it undermines all of the rest of the work in the report and the conclusions it leads to.
The scientists say so, therefore the commenter is wrong? This still doesn't explain why the above is wrong. Attacking the premises of an argument is sound logic, and should be welcome. Ad hominem arguments should be called out.
