Yeah, I've thought of that 'touching the ground thing'. But by that logic, all pure water Pokemon should never come to land, and we've seen that before.
The best way I figure is that Normal-type suggests a sort of real-world ness to the Pokemon. Flying-Normal Pokemon tend to look very basic without any flair. The unusual shape and colors of the bird make it look unnatural, so I guess that gives it the right to be pure flying.
Interesting note (Oh, I'll be pun-ished.) - the sybol of Perrapu reminds me of something Meowth 346 once said about Pokemon having a psuedo-type of Sound with the soundproof ability. I'll bet this Pokemon will have that. Although I was half-expecting them to actually make a Sound-type. Looks like that idea isn't going to go through...
And it looks like Pelipper and this thing are going to have very similar sounding Japanese names. Time for their Seel/Spheal I guess.