Yes, I have heard that before.
Because I have never heard of
Myra Hindley (I am American), it doesn't really phase me, and
Myra has been in the top 1000 year pretty much since the name statistics were first recorded.
I think the disdain for
Myra is regional enough so that I would still use it. After all, I am sure the name isn't the reason why the person did something wicked.