I'm pretty sure it requires you to scan the passport, but when I think about it the same optical reader should also be able to scan the machine readable zone of the EID in that case. The EID is linked to your UID which is the database key they use, so the same data should be accessible.

The DXB eGates that accept EID read the data from the Chip rather than the MRZ and I'm not sure what database that queries. It also seems anecdotally to be a lot slower and less accurate than the AUH gates in my experience - maybe 50% or more EID users have trouble with the DXB eGates while those using passport at AUH I find have almost no issues.