Not sure how failing to veto when she could on a conscience issue, is dictatorial, though again if I were the king of the world I wouldn’t have someone like this being a monarch of supposedly independent countries. Canada? Australia?
As I said before — the constitutions (and, by extension, constitutional law) in the Commonwealth Realm countries are quite different from that of the U.S.A.
Your premise (that she could “veto”) is incorrect. You could visit a law library in Canada for the reasons why — it takes a lot of explaining. The customs and practices (and precedents) of every nation in the Realm, going back hundreds of years, have to be taken into account. Bottom line — if the Queen had withheld assent from this bill; it would likely be the last official act of any British Monarch.
And yes, “By the Grace of God of the United Kingdom, Canada and Her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith” Queen Elizabeth is Canada’s Queen and Head of State.