The Ascend 5W is indeed a GSM only phone. It simply lacks that hardware (radios) to be provisioned on a CDMA network.
Of the phones currently sold by Republic, only the Moto G4, Moto G5+ and Samsung Galaxy S7 edge may currently be provisioned with CDMA coverage. Of the three phones currently on sale. one the G5+ may indeed be provisioned with CDMA coverage. At $224 for a 64 GB phone, it’s a steal in my opinion.
Generally, GSM only phones will tend to be less expensive than phones capable of being provisioned on either GSM or CDMA networks due to economies of scale. GSM only phones may be activated almost anywhere in the world. Phones capable of being used on CDMA networks are, for the most part, needed only in North America. As large as the U.S. market is, the rest of the world is larger.