Doesn't change the fact that GPU mining YACoin is possible (and possibly already achieved). It's pretty much wrong saying that YACoin is only CPU minable.
Learn to read....
Using scrypt(N, 1, 1) means that only solo cpu mining will work
until someone will fork mining pool software or implement GPU miner.
However, it's not that simple at all.
In response to that fork (and GPUs actually mining) not only will the difficulty increase, but more importantly, so will the N-scaling factor, which make Scrypt harder for GPUs. See za post by YaCoin author.
May 14, N=64, 8Kb
May 17, N=128, 16Kb
May 20, N=256, 32Kb
May 29, N=512, 64Kb
https://bitcointalk.org/index.php?topic=196196.msg2083635#msg2083635