Ferocitus
Deity
As said it's a matter of trust.
If you don't trust the apps to do what it says it does, then even the source code of the Red Shell DLL wont prove anything for you, because if it does something malicious, it can be included in other parts of the software.
By extension, how can we know that the mac version is not using that tool: there are possibilities to include it in another form than an external DLL
Yes, it's a matter of trust, and it's always prudent, from a security
pov, to assume that the code is not safe until the source code has
been scrutinised.
Of course, you can't trust routers, comms hardware and the software
running them either.
I prefer Stallman's hard line over corporate assurances.
