Sure. S-expressions[1] are a notation for nested data structures. They can be used to spell out data as well as code. In fact both code and data look the same when expressed using s-expressions.[2]
When the article's author describes both code and data using JSON, it sounds a little strange to me. While JSON is capable to describing nested data structures, JSON's syntax is much more verbose than s-expressions. I feel that since s-expressions have been around for about 60 years that the author should be familiar with them and address why a JSON encoding is superior to s-expressions for this use case.