I'm pretty sure they're referring to the idea of a "highly engaged effective altruist", which is a common metric used by EA community builders. 

The Centre for Effective Altruism defines it as:

...people who are motivated in part by an impartial care for others, who are thinking very carefully about how they can best help others, and who are taking some significant actions to help (most likely through their careers).

It might make sense for the author to clarify this if so :)

Thank you so much for posting this, Nathan and Matthew! I think there's a ton of relatively neglected truths in here, especially around the college club market point. I'll be sharing this with my uni group network.