I think he's mainly trying to weed out people with one-off transactional sales, like online stores. Josh has mentioned a few times that occasionally they'll sign up and end up churning out because the model just doesn't work for them. But yeah, it could definitely work if you ran like a membership site off of Stripe. Not exactly a SaaS, but same sorta rules apply.
Really any "recurring subscription" business will work just fine as long as you're using subscriptions/plans within Stripe. "SaaS" is indeed infinitely easier to market to and in reality is the lions share of "recurring billing businesses that actually make money" :)
