I'm sure that Napoli lost this game on purpose. They are not in the best position in the Serie A standings and they need to keep playing in the Champions League. The Italian Cup is not important for them and they will not waste strength on it. The main thing for them is to improve their position in Serie A and try their luck in the Champions League.
If Napoli is still trying to improve its position in the Serie A standings, of course Napoli must always consider winning and it would be very unreasonable if Napoli deliberately lost the Coppa Italia to a team lower than them. Apart from that, Napoli also cannot give an excuse if they deliberately lost just because they are still in the Champions League this season, because their fans will certainly be very disappointed if Napoli admits that they deliberately lost a certain match even though it was outside of the Champions League competition.