I believe the better way of explaining this might be that the NDA may well expire contractually but the information (testing data) is legally the property of TC.
Therefore, STWA would require TC's approval to disclose.
STWA will certainly have access to all of the data for their use but ownership would be retained by TC.
Others may argue that all contracts expire which is true but ownership doesn't. So this argument shows little knowledge of these types of contractual arrangements.