Note for non-Brits: Tesco are the UK's largest supermarket chain, have various trademark spin-offs including banking and insurance and MVNO cellphone arms, and are pretty much the British equivalent of WalMart.
Although, confusingly, ASDA is actually the Walmart of the UK and Fresh & Easy is the Tesco of the US.
Illustrates the danger of passing all PR functions to, well, PR people. They have obviously taken on trust the rational provided to them by their IT contact. We all know this tweet is ridiculous - who are they to know different?