...I have stolen the real Horcrux and intend to destroy it as soon as I can. I face death in the hope that when u meet your match, u will be mortal once more. R.A.B. (HBP pg. 609/569)
Dumbledore showed Harry the complete Lost Prophecy. We learn that Neville could also have been the Chosen One. Dumbledore tells us this, and then insists it could only have been Harry. Why mention it then, in the first place?