I think he is expressing dissatisfaction with QM rather than endorsing MWI. I found a different quote, from 1950, that seems to support the former.

For it is just because they prohibit our asking what really “is”, that is, which state of affairs really occurs in the individual case, that the positivists succeed in making us settle for a kind of collective description. They accuse us of metaphysical heresy if we want to adhere to this “reality”. . . . The present quantum mechanics supplies no equivalent. It is not conscious of the problem at all; it passes it by with blithe disinterest.

That isn't that clear a statement of his views, but it is from a letter written in reply to Einstein, who said

I am as convinced as ever that the wave representation of matter is an incomplete representation of the state of affairs, no matter how practically useful it has proved itself to be. The prettiest way to show this is by your example with the cat. . . .

If one attempts to interpret the ψ-function as a complete description of a state, independent of whether or not it is observed, then this means that at the time in question the cat is neither alive nor pulverized. But one or the other situation would be realized by making an observation.

(Both quotes are taken from Karl Przibram's Letters on wave mechanics: Schrodinger, Planck, Einstein, Lorentz p. 35-38.)

This is clearly against quantum mechanics rather in support of MWI. They both realize that QM's ontology needs to be revised, but neither knows how.