A deist who decides that God is outside the realm of science is a theist yet can still be a scientist.
An omniscient god is demonstrably false when he is recorded as calling "Mulligan" on creation and staging a do-over after the Noahide flood.
A god can be a god without being omniscient. There are god concepts other that the judeo-christian concept of god. Deists believe in a deity with absolute power over creation but don't believe in the Noahide flood, or any other myths of traditional religions.