Um, yahoo search lists only one John Hospers living in CA. If anyone wants to call him up and confirm that would be nice, though I'd bet he wouldn't like to be swarmed with phone calls .
Funny you should post that.
I just got an email from the aol email address which gave me the same phone number and confirmed that he wrote the endorsement. (But, of course, that isn't exactly an ironclad authentication...)
I gave him the URL of this thread and asked him if he'd care to discuss with us.