The problems with the Nazi-pink triangle explanation are multiple. It is too simple. The symbolic messages are too mixed.The timing is wrong. Where do I begin?
It is too simple If I am sure about anything after decades of studying fashion, it is that simple connections make great stories, but usually bad explanations. Pink and blue symbolism became popular in the United States over the course of several generations, and varied considerably by region, even after 1940. This made me skeptical that pink triangles in Germany somehow quickly effected change in the US. Furthermore, the pink triangle was not a universal symbol for homosexuality in the German camps. It is most commonly associated with Dachau (other camps had their own systems) and was used for sexual offenders, not just for homosexual men.
The symbolic messages are too mixed. Pink symbolizes male homosexuality. Or femininity. Or communist sympathies. Or romance. Or sexuality (in the olden days, pornographic images that showed female genitals were called "pink shots".) You get the picture.
The timing is wrong. The use of pink badges was more common in the middle and later years of the war, and the general American public knew very little about the realities and details of the concentration camps until later. My research places the "tipping point" for pink being considered a feminine color in most (not all!!) of the U.S. sometime in the 1930s, later rather than earlier. Some articles turn this into "around 1940" in order to connect it with the Nazi pink triangle. tsk tsk.
The other timing issue is that in the 1940s and 1950s, homosexuality was still a taboo subject. The pink triangle did not really emerge in the American symbolic lexicon until the late 1970s at the earliest, and for many straight Americans was unknown until the 1990s. This makes it unlikely that parents and manufacturers associated pink with the Nazi symbolism in the 1940s.
The bottom line, in my opinion, is that the dots between the Nazi pink triangle and pink as a little girls' color are strictly imaginary.