I have considered the possibility of a reconnaissance mission before but found it being less likely. Firstly, because the aircraft had flown at a relatively high altitude of 39,000 ft, secondly, because there probably still was a marine cloud layer underneath.
Yes....debris recon missions would seem unlikely at such altitude....I think they track the debris immediately, and/or they let it sink into the ocean fathoms....if it is not float-able debris.
"Can you verify if a NOTAM was issued for W-532n/e/s on June 23rd 2014?"
Are NOTAMs required over/around Vandenberg AFB ?....I think it's permanently restricted airspace.
But if debris may fall, I think NOTMARs are (Notice To Mariners).
(kinda off topic, but interesting)