For what it's worth, he did have means, motive and opportunity. Fred making the logical, if erroneous, deduction that Alistair Krei was Yokai.
The movie also shows that technology itself is not good or bad it simply is and it is humans that can use it for good and bad - as exemplified by Baymax. The heroes are geeks/nerds who revel in their creations for the joy of creating and the potential good that their creations can give to society.