It would really surprise me if the flea beetles didn't go after the daikon radish.
They chew on all the brassicas and especially like the more common radish.
The way I have eaten daikon is in Vietnamese sandwiches. I tried a daikon variety in the garden that was supposed to be for use a greens crop. Planting early, planting late - it didn't work. With little leaf growth, the plants too quickly bolted to seed ... so I had some seed pods to enjoy. They were growing in the home garden where flea beetles are not much of a problem. In the big veggie garden - they are out there in big numbers every year. Perhaps, because of the wild mustard and alfalfa which is available even if they don't happen onto my garden plants.
Steve