RM or railways can answer any thing. There are many instants we can quote where train class changed.
Example Sesaram - Delhi AC express converted as Garibrath later extended.
Some of Karmabhumi exp trains 3A, 2A coaches and also for some YUVA trains.
SO these all reasons are just fullstop the issue but actually there is no such hard rule that AC exp...
more... shouldn't be converted in Non AC exp.
Even hwh-puro duranto, CBE-MAS duranto converted as Shatabdi exp. Like that many incidents are there. Hope RM thinks abt the loss this train making railways before replying.