I am doing some rewriting in response to comments here, and that last paragraph is already being changed to reflect some of your concerns. My stuff normally starts a little extreme and then gets moderated as I re-read it a few times.
In any case, your computer is yours, and you can do whatever you want on it. Since I am speaking to the business manager, it's not the employee's computer, it's owned by the business for business use, and it's the interests of the business that need protection.
The business person has several problems here. One is the workload of the computer, which may or may not affect productivity. Another problem is inability to tell what content on the computer is legitimate and what is not, because s/he doesn't know where it came from. If the machine has a popular file-sharing program on it, the chances of copyright violation are very high. If it just has an mp3 player on it, then it's a much more open question, but the RIAA wouldn't be able to find it anyway. An additional problem is the adware / spyware, which tends to destabilize computers, often forcing a service call.