Can a claim for unjust enrichment be dismissed after a summary trial under Rule 9-5(1)(a)?

I note that Kosaka v. Chan was not a case in which the pleadings were struck under Rule 9-5(1)(a), but rather a case in which the plaintiff’s claim was dismissed after a summary trial under Rule 9-7. In other words, the claim was allowed to proceed to a ruling on the merits, and the trial judge ultimately dismissed the action because, among other things, the plaintiff failed to establish absence of a juristic reason for the defendant’s enrichment. Thus, Kosaka v. Chan is compelling authority for the proposition that a valid and subsisting contact can be taken as conclusive evidence of a “juristic reason” for a benefit, so as to defeat a claim for unjust enrichment. However, it is not at all clear to me that this reasoning could be extended so far as to bar a claim of unjust enrichment as an alternative to a claim of breach of contract.