Being a moderator does not make you an employee of stackexchange. There is no employee-employer relationship, as such, laws governing those relationships don't apply.
What constitutes an employee-employer relationship?
This can be difficult to answer. This question has been raised recently because of Uber. Uber drivers were suing uber for workers' rights violations, asserting that as drivers they were employees of uber, and demanded the same rights as workers everywhere.
Uber contested this, stating that the drivers were not employees, but users of the Uber app, and that technically all "drivers" were really carpoolers, and Uber offered a service to these carpoolers to find others to ride share with. As such Uber was selling a service to these drivers rather than hiring them.
I cannot remember the case name, but in the UK I believe it was held that certain factors determine if there is an employee-employer relationship, including: whether there was any remuneration for the work, what kind of remuneration was there, did one or both parties consider their relationship as employee-employer, was there any oral or written agreement purporting to be an employment contract, etc.