the possibility that the Court will impose a preliminary injunction
That statement was literally true even before the TRO was granted. But it is easy to understand why the FTC would not want to credit a mere possibility as a justification for a restraint of trade.
I think it is far different when a District Judge has found a likelihood of infringement worthy of injunctive relief AFTER both parties have been heard and issued a TRO.
Calling a settlement collusive in that context should not fly, IMO.