I wonder if Tesco fully appreciated the level of press coverage it would receive by alerting the public to the lack of supply for certain Unilever brands, but it is being hailed as marketing genius.
In this crazy world of Brexit, standing up for the end consumer and protecting their interests and the pennies in their pockets, will win great support, as this article explains.
Bernbach famously coined "a principle isn't a principle until it costs you money." This move will cost Tesco plenty of money but its effect on the perception of the business could be dramatic. Blanket media coverage standing up for the British shopper - there are not enough TV ads in a year that it could run to achieve this
http://www.thedrum.com/news/2016/10/13/the-tesco-war-with-unilever-brave-british-coup