i dunno. it lubricates the dental/gingival surfaces but also the particles. i would think it depends on how firmly embedded the particles are, and whether the particles are superficially hydrophobic (e.g. shreds of greasy meat).
note, brushing and flossing are totally different things. brushing is mostly to scrub away acid and break apart plaque. flossing (swishing, waterpik, etc.) is mostly to remove particles of food from gingival pockets, so they don't fester in your gums.
at any rate, what harm is it doing? why suddenly all the concern for the 20 minutes a day a few anonymous people are 'wasting' on something which is probably helpful and, at worst, only useless?
[ah, okay, yeah, doing this instead of brushing is a terrible idea. i missed that part.]