Yes. And since I don't think you actually have read the OMs, and doubt your ability to locate them yourself, here you go:
http://www.fedcourt.gov.au/__data/assets/pdf_file/0015/25233/Essendon-Orginating-Appliation.pdf
http://www.fedcourt.gov.au/__data/assets/pdf_file/0016/25234/Hird-Originating-Application.pdf
Please point me to where you say that Essendon is trying to prevent the players from taking legal action against Essendon.
Its just logic. If the players go down they will take action against their employer over damages caused by their be negligent practices. The argument is that Essendon want to stop the case progressin to avoid being sued.
Pretty simpple.