It's not actually eink (aka electronic paper). It's an LCD screen with a filter to help glare. Clearly deceptive marketing and worse, they have "friends of employees" advertising it as eink.
Do you have a source for this? I was interested in this device until I heard this, but I haven't found anything that states what the display technology actually is.
The closest thing I've found to being suspicious is that their site uses terms like "paper-like finish", which doesn't seem too out-of-the-norm for this category of device, and they have marketing photos implying that usability in the sun is on-par with other e-ink devices.
The HN thread has comments by "founders" admitting it's a transreflective LCD. They claim it's super-duper customized but it's still an LCD.
I also found a a reddit thread where it was being advertized as e-ink and a company rep came in and admitted it as an LCD and that the article came from a friend of an employee, but I'm not finding the thread again now from a quick search.