Looking more closely at the interview, it doesn't lokk like he's got anything, just more "someone told me theuy oncw worked somewhere secret and saw something" - no documentation, no actual evidence, just more rumour.
The Japanese balloon stuff has been around for a while, man-carrying Fugos and all (previopusly linked with Roswell), but he doesn't seem to very clued up on the secret US balloon programs of the era, or their UK counterparts. (Curtis Peebles book on the Moby Dick Project is very good on this.) Obscure topics, granted, but essential for this kind of thing. And you'd also have to look at the US military's record in this kind of experimantation and the sort of protocols they were forced to follow. The dodgy stuff tends very much to be in places where US law does not apply.
So it l;ooks very much like he's applyoing another layer of gloss to the X-Files version of the myth, rather than trying to strip away the layers to get at the truth.