In proceedings brought under section 4, the insurer is entitled to rely on any defence or any other matter in answer to the claim or in reduction of its liability to the claimant:
(a) that the insurer would have been entitled to rely on in a claim made by the insured person under the contract of insurance, or
(b) that the insured person would have been entitled to rely on in proceedings brought by the claimant against the insured person in respect of the insured liability.