Lungu deported Simwaya in December last year after linking him to Al-Qaeda and that he was a threat to national security.
Lusaka High Court judge Chalwe Mchenga, however, dismissed the deportation order describing the decision to effect the deportation as misplaced and contrary to natural justice.
Lungu said police and other security wings are still investigating Simwaya and that he will eventually be evicted again.
He said he will not allow peace to be threatened by people like Simwaya who have links with Al-Qaeda.
Simwaya had successfully challenged his deportation to Rwanda and although he has returned home, government is keen on finding other charges to deport him for the second time.