Atlantis, thanks for pointing those out.
I reread the letter and now I'm skeptical too. What caught my eye is where it says something about 'ascertain the meaning of prophecies.' Ascertain is a very large word for Watchtower. The rest of it on a second reading also doesn't sound like Watchtower... it's hard to explain why, but I get a different sense from it than I do from letters to the body of Elders, which always comes across like cheery well-polished propaganda, this seems more slapdash, it doesn't flow as nicely from sentence to sentence, it's awkward. And the spelling errors is very unlike Watchtower.