I believe someone is already GPU mining it and planning to dump thousands of coins.
And your evidence for this is what?
People kept believing that Primecoin was being GPU mined, without any evidence. And still no-one has admitted to being able to mine it on GPUs, the two well publicised efforts both ending in failure.
Any thing that is computationally intensive can be mined faster on the GPU employing 1000s of hardware threads, so I find it impossible to believe that Primecoin is a CPU-only coin.