Might be because he is so quick to blame everything but the products he supplies, im sorry but 0.4:1 comp wont make 20-30rwkws difference, the engine would need maybe 2 degrees more timing to make up the difference, if he was running 7:1 comp than yeah sure it would make a big difference.
For all we know the tuner has a low reading dyno or it was a hot day or the cam timing is out, or there is a leak somewhere.
There are a million things it could be, but saying that having lower compression will mean that the dyno curve moves to the right is just a bit silly, especially with standard cams, sure off boost it might be a little bit softer, but with a good tuner the difference should be able to be made up with fuel and timing changes.
Of course Tao isnt going to say his turbo is at fault, because he builds/sells them.
*waits for all the fan boys*