Given that most of us don't have the time nor expertise to validate his claim, it is perfectly reasonable to take into account the reputation of the author, the

Given that most of us don't have the time nor expertise to validate his claim, it is perfectly reasonable to take into account the reputation of the author, the reputation of the journals that published his work, as well as obvious problems in his methodology. That doesn't disprove his claims but there are enough warning flags that should leave you highly skeptical of them.