I think the author and you might have different understandings of "lazy". If I pursue a hobby for an afternoon with no financial upside (say, building model kits or painting) I might consider that a "lazy Sunday".

I was productive, insofar as I pursued an interest, but I was not productive in the "producing salable work".

I think there's a universe where lazy can mean different things for different people. For some that's lying on the couch, others might read or write or pursue art and music.