Because the CEL codes pointed to a problem with the solenoids. The T/C light is generated by the solenoid related codes. The T/C light can also be triggered by numerous other problems.

In other words, the T/C light does not necessarily indicate a problem being the camshaft actuator solenoids.

 

And remember that I have a friend whose HHR is factory stock and has the T/C code. In other words, modifying the intake or exhaust have nothing to do with the code problem.