The Big Book and the 12 & 12 make it very clear that as alcoholics, we have lost the power of choice when it comes to drinking. We are utterly powerless, and need outside help to overcome an obsession that is so overpowering that "no amount of human willpower could break it." - 12 & 12, page 22.
Sure, in a literal sense any alcoholic who drinks must 'choose' to pick up that drink and put it to his or her lips. But what's the point in focusing on the problem more so than the solution?
I think that insisting that someone say they 'chose' to drink rather than 'slipped' is unnecessarily punitive and also beside the point. Why not just say they drank, period?