What is the ruling on someone who extends his leg towards a bag containing papers upon which the name of Allah the Almighty is written, knowing that the observer is aware of this but does not caution him out of shyness, despite detesting the act in his heart?

There is no dislike (makrooh) in placing books of knowledge behind one's back as long as there is no intention of disrespecting them. The words of the Shafi'is indicate the absence of dislike unless disrespect is intended, for they explicitly stated the permissibility of doing so with the Mushaf (copy of the Qur'an), and thus it is even more permissible with other books of knowledge. This is similar to spitting on a tablet to erase it because it is a means (to an end), and placing the Mushaf on a shelf in a cupboard, and so on.

Therefore, there is no sin upon you for what has occurred.