Q:

Noun for the act of withholding?

Merriam gives me "withholder", which is indeed a noun, but not for the act. 
Sample use in a sentence:
"Even private schools have some contact with the outside world, preventing the withholdment (sic) of certain facts."
Naturally, an alternative could be to substitute the double negative with "encouraging the acquisition of certain facts", but this changes the meaning completely and is untrue, and is therefore not what I want to write.

A:

Withholding is the word you want. It acts as a noun in this context. See this Wikipedia article.

