Yes. This is correct. I dont think its for life,but you definately cannot sit for the CAE-Indigo exam again.
Quoted from their e-mail-
Please ignore this mail:
· If you are A320 typerated.
· If you have already appeared for the CAE-IndiGo assessment in the last three months and have not completed the cool off period of three months
· If you did not clear the interview round(with IndiGo)