It's the first time I've heard that word. I can guess that it's supposed to mean "solo entrepreneur", but it's a silly-sounding word to me. Basically, it's slang, which is unusual in a long article such as this.

It's being used since 1990s as per Oxford dictionary[1]. I asked because I thought it's one of the words which has become uncool to use.

[1] https://en.oxforddictionaries.com/definition/solopreneur