On their dataset page, they say that only the 25,000 image collection is available commercial use, _not_ their 2 million image dataset.
This makes the claim in the title basically false, no?
EDIT:
In fact, once you start going through mandatory pre-download questionnaire they limit usage even further.
As a heads up, the dataset is for research purposes. It is not to be used to bulk download the images for usage or viewing. Both unsplash.com and our API are free products designed for accessing and downloading the images.