I suppose it helps to floss before brushing (as recommended) but for me personally the stray particle isn't something I've worried about. In my mind, the added benefit of retaining the fluoride longer outweighs the downsides of microparticles of food.
Honestly, the timing of flossing is the least important thing about it, considering most people are averse to even doing it. The payoff with flossing before brushing is that any gunk that gets brought out and left over after rinsing gets scrubbed away during brushing.
