As Johandea wrote it it's a temporary "work around" that has been put in place during the time the case will be decided upon. The workers in question (union members within the postal services, and all others) are still on strike.

I have a hard time seeing that they will ever win over the unions in court and that the court will deem the strike illegal and force unions that are on strike to revoke it.

As said, (sorry but I miss wrote "protest") the right to strike is defended by law.