Actually, you might have a point there. I checked the FAQs again and saw this bit on releases and trademarks:

https://help.unsplash.com/en/articles/2612329-releases-and-trademarks

"Recognizable people, including celebrities, have the right to profit from commercial use of their name, image and likeness as well as the right to object to their name, image or likeness being used without approval."

I am making my own interpretation here, but I would expect that this is more likely to be a problem if somebody has been photographed unexpectedly or without their permission in the first place. But if the photo looks like the model was allowing the photo to be taken of them, it's likely to be fine as they probably knew that it was going to be submitted to a photo library. But I accept that I am making an assumpton there, and there will occasionally be exceptions to that.

"While photographers agree that photos uploaded to Unsplash have model releases, there is no reasonable way for us to monitor all photos that get uploaded to Unsplash. We cannot make any guarantees about the scope of permitted uses. We recommend reaching out to the photographer to clarify whether they have a model or property release. You can do this directly via the ‘message’ button on the photographer’s profile."

Unsplash knows that 99.99% of people who use their photos are not going to check. Especially in a situation like with Medium where writers are able to quickly find Unsplash photos from within Medium.

It seems that Unsplash are including these bits in their terms to cover themselves in case anything goes wrong. But the chances of that happening are very slim. Of course, we all have to decide for ourselves what risks we are happy to take. And if you are running a publication, then that potential risk will feel greater.