Exactly. If anyone sues over previous WMSC decisions the FIA is, according to legal opinion, stuffed.
Not necessarily. If previously an "offender" accepted the FIA's verdict and punishment, it will be much more difficult for it, retrospectively, to challenge that verdict.
Briatore never accepted the verdict, and within a reasonable time went outside the FIA regulatory system in order to challenge it.
Also, one of Briatore's arguments which IINM the French court supported was that the FIA executive had acted as both claimant and jury. That is, the FIA executive (WMSC) raised the charges against Renault, et al. and then the same WMSC sat in judgment of its own arguments.
In the most obvious and outrageous example of WMSC abuses, the $100m fine and the rest, it was an entrant that raised the charges, the FIA executive investigated, the complainant then made its arguments to the WMSC, who sat in judgment.