What is the test for a claim under a disability policy when the policy was rescinded in 1985?

The case that bears some resemblance to the situation here is MacMillan v. Constellation Life, [2006] N.S.J. No. 396 (S.C.). The plaintiff brought an action under a disability policy in 2003 alleging that the policy should not have been rescinded in 1985. On an application for summary judgment, the plaintiff’s claim was dismissed. In particular, the court stated at para. 26: Under that circumstance the plaintiff/respondent must now establish a claim having a real chance of success. The plaintiff argues that the limitation period did not run against him since he was of unsound mind for the whole of the period. The burden is on the plaintiff to establish on a preponderance of evidence that he was of unsound mind as claimed.