Mediation is a form of dispute resolution that’s different from courts and arbitration in that it is non-combative in nature. The goal of mediation is to work out mutually agreeable solutions to problems through dialogue. As a result, these win-win agreements are more likely to be stuck to and preserve the relationship between the parties involved. In fact, the organizing countries involved in setting up the IOMed (led by China and includes Cuba, Pakistan, and Indonesia) see it as an alternative to the ICJ and the ICC.
The IOMed, I think, is a great sign and symbol of the decline of Western hegemony—not only is it independent from the West, but the foundations of mediation itself are about cooperation and non-violence. The idea of someone—anyone—being able to dictate what is right and wrong to others goes against what mediation is all about.
Edit: link to the official statement from the Foreign Minister