The most relevant definition, which is actually under "censor (verb)", I reproduce here:

> to examine in order to suppress (see suppress sense 2) or delete anything considered objectionable

Piracy is not typically considered bad due to being "objectionable", it is considered bad because many people/societies consider it equivalent to theft. You can obviously stretch the definition of objectionable to mean that, but it is on you to demonstrate that is a reasonable stretch. Blocking out sex scenes from a movie and removing pirated materials are obviously different actions, and this definition clearly refers to the former.