Not sure what he meant by "object-oriented", but he - as the other members of the IFIP - was well aware of Simula 67, and he belonged to the faction that rejected van Wijngaarden's proposal and regarded Simula 67 as "a more fruitful development" [1]. So - if he said or wrote that at all - it's likely related to what Kay understood by the term, or the implementation as a dynamically typed, originally interpreted language done at Xerox PARC, not to the kind of "object-orientation" for which Simula 67 is recognized today (remember that the term "object-oriented" was originally not applied to Simula 67 by the public, but to Smalltalk).
[1] https://www.researchgate.net/publication/2948437_Edsger_Dijk...