You can easily introduce a rogue organism that may sour the beer by removing the lid at the wrong stage in the process. The best thing to do is trust that your yeast is functioning perfectly. If you want to check on the activity level of the beer, shine a strong flashlight on the outside of the keg to see if fine bubbles are still rising, or if there is yeast foam still floating on the beer.

Removing the krausen kollar after a week as instructed poses minimal risk for contamination as there is still so much CO2 present that the likelihood of a rogue organism making it to the new beer at this point is infinitesimal.