Here's my little bit of speculation...just for fun:

I do think, though, that his name is an actual word...it seems to need to be something that can be uttered, as River says it to him in The Library if I remember correctly.

My only problem with this theory (about the time lock) is that River does actually say The Doctor's name to him in The Library. If it is merely a problem of it being "said" then the time lock would have opened at that point, wouldn't it?

Further proof that Bella is The Worst.

Is it because they might have inspired: "Birdemic: Shock and Terror"?