Are you saying they allow it from a technological perspective but have rules that people should use headphones, which then aren't enforced? I really hope BA will be strict on this although cabin crew are already stretched. Rest assured if BA have a rule and people aren't following it, I will be telling them politely to stop and if they don't I'll be telling them where they should shove their devices discreetly asking the CSM to intervene when they have a minute.