He's currently testing other themes for similar censors, but it looks like Apple didn't want people spoofing Universal Studios trailers. Because I'm sure "Me and my dog go to the beach" could easily be confused with "Marley and Me,"* right?
As you can see in the picture, Tarik tried to input Universal for the "studio name" field. iMovie detected this, and substituted the hyphens. Further, he reports you're able to use the string 'Universal' in other themes, just not in this one. Was this accommodation reached directly with Universal, perhaps to prevent any derailing of Universal's deal for distribution on iTunes and Apple TV? I doubt we'll ever know.
Let us know in the comments if you find more examples of this.
UPDATE: iMovie '11 won't let you write in the text string "Paramount" without the adding the hyphenations either. Image on the next page.
*Yeah, I know "Marley and Me" is a 20th Century Fox production.
Paramount on the mountain-with-stars is disallowed.