I guess I would say no, but let me actually explain why. This is really an onus of proof, I guess, rather than a burden of proof, and this is fairly common in the kinds of public regulatory prosecution standards coming out of R. v. Sault Ste. Marie in Canada.
So in this case, there's an onus on a plaintiff to put forward enough evidence that a court could find on a balance of probabilities. So if a plaintiff doesn't meet that, doesn't get to the 51% standard--that's what prima facie means in this case--then the other side doesn't have to say anything and they won't win. Once the plaintiff meets that standard, in the absence of the defendant saying anything, they're going to lose.