I think the keyboard uses a magnet to detect when it is deployed, and that is what is being tripped by the cases' magnetic clasp.
After playing about with the case, trying to find all the ways to turn my TP2 on with it, (never turns on inside the case, mine is nowhere near as magnetic on the inside as it is on the outside) i found that the magnet can also rotate the screen disabling the onscreen input at the same time, just like when the keyboard is deployed.
If my theory is correct, then if you can find a way to disable the power on with keyboard slide (has anyone figured this out already?) then your problems with the case should be solved.
Or you could try and demagnetising the magnet a bit, perhaps your magnet is mega-powerful and thats why its able to trip the sensor while inside the pouch.