It doesn't really matter too much about whether people know who The Stig is or not, it won't ruin the show, if it means that much that nobody knows who he is then just get another one who nobody knows the identity of.
The bigger picture is that the BBC is defending a contract and I think that they are entitled to do this. Some of the 'License Payers' money goes towards legal costs, every year, this year is no different it's just that the case is higher profile.
Oh I think there is a great justification here. Just imagine the sharp fall in sales of those exceptionally humorous t shirts that have displayed 'I am the Stig'.