I feel like they probably could use another mammals neural cells and get similar results, but they use human cells because it'll get them attention - and that kind of rubs me the wrong way.
But yes, I agree that they're likely using human brain cells mainly because it's attention-getting.
The Doom project is mostly a bit of fun that demonstrates how quickly someone new to the field can see real results with our platform. Our data scientists believe that biological learning was demonstrated in this case.