So, I do not know the ins and outs of the law, but it seems to me he really has no case here. How I understand it:
He admitted to using Deer Antler spray (not knowing it contained any illegal substances, which seems very reckless on his part).
The Tour thus put disciplinary action in place.
Word Anti Doping Agency then says the illegal substance in the spray is no longer illegal/prohibited.
Vijay appeals the inital ruling.
The Tour retracks the punishment.
Now Vijay is sueing (ruining his reputation, Tour being careless and also singling him out, etc.
Those who know the law, is this even a case? What exactly did they do wrong? The only potential thing I can think of is maybe they went off his admission instead of an actual test (not sure).