I believe the host notes it right in the podcast... They are NPR (public radio) and are too poor to afford the dot-com! (PS - .Org and other extensions certainly have their place in the domain ecosystem, they will just never overcome the first-mover advantage of dot-com, nor from a domaining perspective will they ever generate as much consistent value IMHO... Just look at com vs. other extensions on dnjournal on any given week... We've been having this same discussion for years; first with dot-net, then dot-info, dot-mobi etc. and now with new extensions... Dot-com always prevails - It's just simple math...)
.Com is king, but you'll need good .com to sell them. They are all taken. Simple as that!
Ps. Still you can make money from starting investing in .com. But you need to spend a lot of time, be smart, rely on data and probably also a pocket full of cash to invest. Hand registering .com in 2018 will not make you rich. At least not 99% of us.