I would expect all FAI team members to have strong math skills in addition to whatever other background they may have, and I expect them to approach the psychological aspects of the problem with greater rigor than is typical of mainstream psychology, and that their math backgrounds will contribute to this. But I think that mainstream psychology would be of some use to them, even if just to provide some concepts to be explored more rigorously.
I would expect all FAI team members to have strong math skills in addition to whatever other background they may have, and I expect them to approach the psychological aspects of the problem with greater rigor than is typical of mainstream psychology, and that their math backgrounds will contribute to this. But I think that mainstream psychology would be of some use to them, even if just to provide some concepts to be explored more rigorously.