That isnt about not taking it seriously.
This is a failure of following basic military standards. Soldiers are never allowed to be fed with civilian food due to what just happened, intentional poisoning.
Russian military as an organisation is rotten to the core if they can't even be bothered to follow the most basic military practices.
I think you overplay this somewhat, It is true that in british and particularly american military traditions, heavy emphasis is placed on a logistic tail that feeds field i army up through a chain of forward depots to a friendly logistic base.
European continental military tradition place heavy emphasis on troops living off the land when in the field. That includes living off of local civilians when possible. In fact, if forage is available, consumption of forage is to be preferred to the consumption of rations so the rations can be saved in case of emergencies.
During WWII there were lots of accounts of victorious german and russian soldiers being poisoned by the local populations, partisans and insurgents. to deter this kind of attack in order to preserve the army’s ability to live off the land, the reprisals carried out against such attacks were always brutal. often dozens to fifty or a hundred civilians are shot for each soldier sickened or died by poisoned food. sometimes bad luck befall civilians simply because the food the enemy soldiers requisition had gone bad naturally before being consumed.