Why does Hari solicit Raych to go undercover in Part 1 of the novel, Forward the Foundation?

Hari is concerned that as a Dahlite, Raych could be perverted by Joranum's slogans. The chapter alludes to Hari's and Dors' visit to Dahl in the previous novel. Growing conflicts with Dors seem inevitable. This too guarantees complications if not outright conflicts.