I was recently flying in a small airplane (SR22) and the terrain detection system was going bonkers when we were landing saying that terrain was getting close to us. They have all the data, they just need to build in some more protections.
In the context of a pilots mental state verses malicious source code being installed on a set of flight computers, I'd have to say the computer is easier to validate. That many more people have to approve the process. With a pair of pilots the validation process is much smaller and more complex.
We need to stop thinking that machines are flawed and that humans know best. The fact of life is that machines can and do perform better than humans, the only reason flight computers don't currently is that there hasn't been the investment in making them do so. Sensors fail but that is an engineering problem that can be solved.