Problem
Suppose you are hired to work for a super secret three-letter intelligence agency and are tasked with setting up personal computers for clandestine agents working in the field. In the event their cover is blown, the agents need the ability to selectively delete sensitive files from their computer at a moment's notice (i.e. securely wipe the data itself, not just delete the file reference). Why might Btrfs NOT be a good choice in this particular scenario?