Being brain-dead is essentially being dead. Hospitals and surgeons will not operate on you unless you are not expected to recover, or regain consciousness. Being brain-dead, it is also very unlikely that you feel pain. Reflexes can easily still be active even with brain-death, leading to convulsions during surgery. If the author had ever seen a serious car-accident victim in a coma, he wouldn't have second thoughts about organ donation. In his blog post, he is insinuating that you are still a normal, living, conscious human being. You aren't.
Having grown up in a family of medical doctors, I find this blog post appalling.
EDIT: As thebigshane pointed out, my wording is indeed terrible, I wrote my response in a hurry, and I will not edit it to avoid confusion. I do not have any professional medical education, all I know in this field is derived from in-depth conversations and discussions with my parents, whom are both medical doctors. Brain death is indeed classified by the Harvard criteria, but these also include the patient being non-responsive to external stimuli, such as pain (which contradicts the blog post's claim of convulsions during surgery due to the lack of anesthesia).