Is a husband's release clause valid when the husband's will is made in 1988?

In Billing v. Rideout, [1993] N.J. No. 162 (Nfld. S.C), Roberts J. held that a Will made in 1988 was not revoked by a separation agreement entered into in 1990. The release clause read as follows: 12.1 The husband and wife release each other from all claims and rights that he or she may have had or afterwards may acquire, (a) in the estate of the other upon the other dying intestate, whether by way of statutory allowance or right under the laws of any jurisdiction; (b) upon the death of the other, under the laws of any jurisdiction and in particular The Succession Law Reform Act, R.S.O. 1980, chapter 488 and amendments thereto in force from time to time in the Province of Ontario; and (c) to act as executor or administrator of the other’s will or estate.