However, it solves problems the author mentions in his article: you can freely contribute and use the software as you wish, just don't create a competitive company using the recent versions of the sources.
And in 2 years the code becomes true OSS - either MIT or Apache 2.0 (or anything else you want - the FSL itself is pretty short so you can easily adjust it to your needs without spending hours on lawyer consultations).
BTW, the FSL is driven by Sentry, and they have created an org to cover the fair usage licensing: https://fair.io (that's why I have mistyped the FSL name in the original comment).