Okay, but that wouldn't open up the researcher for a lawsuit, it would just provide the company with a PR leg to stand on. Nothing about this case is similar to what you outlined, and would not meet the legal requirements for a successful libel or slander case.
If any company comes out and says the product 100% secure, the tech community basically scoffs at them. It's not a good PR strategy for a company anyways. Now, relying on the reputation of another firm through audits is a totally normal way of doing business. This does not compete with researchers, and has by and large included researchers (stuff like Bug Bounty/Responsible Disclosure programs) as a good control. So any researcher looking for this stuff would likely have a protected way to disclose their findings.
Further, this is supported by another compliance body in the SEC via SOX. There has to be a protected whistleblower program for publicly traded companies. So, the ability to disclose security gaps is not neutered in any way by this court case, no matter how it plays out.