While I do believe that Barnabas awakened every night at dusk in that coffin for hundreds of years, I wonder, if that's so, how he survived without blood?
Some believe he went into a state of suspension somehow; not really cognizant of his surroundings, feeling neither pain nor hunger, perhaps a twilight sleep.
Joshua meant well. He had few choices in this matter, and he could not allow Barnabas to roam the world killing people. However, he also was unable to destroy his only son. Their final scene together is heartbreaking. You KNOW they loved each other, but neither could dare to say it, given the curse and the fact that they'd repressed their feelings for so many years.
Joshua saw this as the only answer for his son. And maybe, just maybe, he HOPED he would be released someday, into a world where miracles were possible and a doctor like Julia or Eric would have a cure for Barnabas' affliction. Who's to say that Joshua's desperate act didn't contain a sliver of hope?
Love, Robin