In 1791, the Reverend William Gregor, an English clergyman and mineralogist, reported that he had discovered a magnetic black sand near the beaches of Cornwall, England. The mineral was named menachanite after the local parish of Menaccan. A few years after Gregor’s discovery, M.H. Klaproth, a German chemist, separated TiO2 from the mineral rutile. Klaproth named the new element titanium after the giants of Greek mythology. In 1825, J.J. Berzelius, a Swedish chemist, performed a crude separation of titanium metal. However, it was not until 1910 that M.A. Hunter, an American chemist, produced pure titanium. W.J. Kroll patented his method for producing titanium metal in 1938. Coincidently, commercial production of titanium metal and TiO2 pigment began in the 1940s.
Maybe this is nothing more than keeping-up with the Russians? The Cold War was already started. Maybe some German materials or German rocket scientist we got was already onto using this type of material? The SR-71 may have been pre-dated by many other plans on the drawing boards decades earlier that were never built or just prototyped or only did basic materials science including the Germans. That would certainly be worth keeping top secret.
The Germans were likely the ones that had some expertise and use of this material during WWII. Regardless, seeing that there was a USA patent for this in 1938, then developing more advanced alloys using titanium for aircraft would already be in high gear to use it for military purposes with prototyping.
I know I've read that first paragraph (the one in blue) somewhere else recently. Have you quoted it, and if so what is the source? If memory serves, there was a great deal of information following it, but perhaps not.