I kind of agree with the no shop item thing, but I am sure the game devs could declare truce periods during a major world wide holiday or for what ever reasons
( exploits, bugs, etc.. ) if it wanted too?
That's not to say they should give any such breaks for any holidays, but again it is likely you will see some players take advantage of such periods of time to defeat enemies while they are opening christmas gifts, toasting in the new year, etc..
It would cause uproar for sure and maybe lead to some players just leaving and not coming back after their town got ransacked and flattened Christmas morning.
So if the devs want to give any truce periods that is up to them and I do not think there needs to be special items to save yourself bought from the item shop.
I am sure the devs will be celebrating some holidays as well sooner or later as well.