While some particularly "sensitive" content might be technically in violation of Chinese law (the law might be wrong even then, but that's a different matter), the majority of the GFW'd content are not illegal, even in China, and very often they would not even be considered sensitive in any way. On the other hand, we do have computer security laws, and disrupting the public Internet via passive and active attacks, as the so-called GFW does, is probably as illegal as they are in developed countries, and I am not aware of any law that grants special permission to such behavior, as it has little to do with either law enforcement or national security.
We still have many "old-thinkers" in high positions that do not realize the importance of network security or even rule of law, let alone free speech. It would be extremely attractive for companies to exploit the naivete of such people for their own profit; in other words, it is protectionism, and a rather corrupt form at that. While I don't know who is actually doing this, I find it rather unlikely that nobody has thought of this.