He's not suggesting that. He's saying that you can always cover yourself legally starting with a conversation.
Hey boss, I'm going to write this wordpress plugin as a side project. I'll be doing on my own time and with my own equipment. I'd like the company to disclaim any right to the code.
9 times out of 10 they will do so. If they don't then you know it's time to polish the resume. As tptacek says elsewhere here. It's too good a job market to risk the legal hassle of working someplace like that.
