Or it could just be a case of someone having the same name, surely Luigi isn't an uncommon name in Italy? Or have other details been released as well (DOB for example) which confirm it's the same guy whose passport was stolen?
Same name and also same age, 37?
Looks quite implausible.
The guy is actually listed in the released Malaysia Airlines flight manifest at #101, with age 37, his actual age. However, according to La Repubblica, not only his family in Cesena (Italy) has talked to him, but also the Italian authorities from the Foreign Minister contacted him and confirmed is alive and did never boarded MAS370.
Incidente Malaysian Airlines, "Papà sto bene, sono in Thailandia". La telefonata di Luigi Maraldi ai genitori - Repubblica.it