Since when it's forbidden to race alone? I use the "private league" mode to rebuild my finances if I'm broken , or when I haven't time to attend an active league.
I think it's not just a bad idea but an unjustified change of rules...
There were too many races where there was only one team after the auto-kick rules was set in place, so to help reduce the strain on the game's servers, any race with one team participating will be skipped.