Ok I think I read you, but lets say his new commercial product was proprietary; the product costs $100. If the license for his original Inbox2 product was GPL, he would be required to distribute the source code on his new product right? So my point is, if its a BSD license he can integrate that code into the $100 product and not have to share the source code. I'm no software license expert so if I'm mistaken please correct me here.
IANAL either, but I still think he'd be free to use his original code in a commercial product. By releasing under GPL, you give others a limited license to redistribute and modify the software subject to some conditions, but you keep all your rights, and you are free to distribute proprietary versions of the code.