From the article, they mention that it was for improving facial recognition unlock. Could it be plausible that they're trying to test facial recognition in real world situations/lighting (e.g. outside in the park on a sunny day)? It also mentions that they were asked to look at notifications while it captured facial data. Could that be for attention recognition?

I mean, it still seems sketchy to me, but it does sound at least somewhat plausible. The article also mentions that the two instances took place in opposite sides of the country (NYC and Miami).