Does Italian administration in the Dodecanese prevent the expulsion of Muslim citizens, contrary to Crete?

Self-evidently yes.

The population exchanges of 1923 dictated that all Muslims in Greece move to Turkey, with the exception of Thrace, and that all Greek Orthodox in Turkey move to Greece, with the exception of Istanbul, Imbros and Tenedos.

In 1923, Crete was part of Greece—though the Muslims of Crete were already fleeing the island after autonomy was granted in 1897. So the Muslims of Crete left for Turkey.

In 1923, the Dodecanese were under Italian administration, and were not part of Greece. Therefore a small Muslim population remains to this day, in Rhodes and Kos.