If Humphries-Bulcher was being paid an American pension while a resident in the United Kingdom, then it is almost certain that he was actually a United States Navy pensioner, and not from the Confederate Navy. Could he have been aboard the USN vessel, USS Alabama, and not the CSN vessel, the CSS Alabama?
Confederate pensions were paid by the states themselves, and the pensioner had to be a resident of that particular state, if he wished to collect a Confederate pension.