I can't tell how big that is, but mine would also probably use it as a nest box because it is enclosed and "hidden". I like to use plastic or rubber feed trays for dust bathing areas, at least in the winter when they're "custom" dust baths (aka a spot they dug under a tree) are inaccessible due to snow because they are easy to dump out when they inevitably get it dirty with poop. I can also put them anywhere I want, and the hens are unlikely to use it as a nest box.
So sure, you could use it as a dust bath, but I predict someone is going to lay eggs in there, and you're going to have trouble cleaning it out unless that is a lot bigger than I'm thinking it is.