As far as I can tell, they're not actually proposing how to achieve this. I can't access the article without a host institution it seems (is there another link?), so I only have the article to go by. RL has been the basis for all robots engaging with the world, and that engagement with the physical world modeled using RL has been promised to make robots that can act like a 2 year old for a long time (see Cynthia Breazeal's work, for example). Yet AFAIK, we haven't actually achieved this as we don't know how to efficiently model the problem to have learning rates that reach anywhere near what we're able to do with DNNs today.
Perhaps someone who has access to the paper can say why this is a milestone? If Patricia Churchland suggests it is, then something new must be happening here.