He could have stopped her as she was reaching for the fruit.
He blew it on many levels.
Yes he did. Eve was deceived, Adam was not. But, even though Eve was deceived, she still sinned, which leads me to believe, that no matter how sincere people are, they can be deceived, and fall for false religions.
Ultimately, all false, works based religions, are from Satan, and I think the first works based, false religious act, was when Adam and Eve tried to cover their sin, by sewing leaves together. I am pretty sure that they repented, and came to saving faith, but here is something I wonder about. They lived for maybe more than 900 years. Somewhere along the line, in those 900 years, I wonder if they ever had some private, late night pillow talk, and told each other, that they sure wish they hadn't eaten the fruit. 😀