[brown9-2]

how do you trust the hosted CI company not to look at your code

One can probably assume that they are not relying upon the secrecy of their code for security.

[hawkice]

There are other reasons to keep code proprietary than fearing a security failure in the event the code leaks.

[chinathrow]

Yes - I think their fraud detection code might be worth some $$$ if sold to the right folks.