There are many uses for the word myself, and to treat it as only a reflexive pronoun is too prescriptive — so prescriptive, in fact, that it would be wrong. The use you give is indeed accepted as correct English, but for a rather tricky reason.
Nonetheless, use of one-word myself to stand in for two-word my self is established and generally accepted: "You seem like a better version of myself" would not normally be objected to, and "I just want to be myself" is perfectly fine.
The first example that they give is exactly the use you're asking about. It's where myself means what it literally describes, my self. Suppose you were going to say my friend instead of myself. That would make sense, wouldn't it?
There is a picture of my friend on the wall.
There is a picture of myself on the wall. same logic
The word is simply being used in a different function than a reflexive pronoun. It's more like a contraction of the two word phrase my self. So it is indeed correct. The Slate.com article gives a lot of examples of both correct and incorrect usage.