As long as you get copyright assignments from anyone sending you patches, you retain the rights to change the license whenever you want, so even if you use the GPL, you could release new versions under a proprietary license.
That said, if you really just 'give up' any commercial hopes, a BSD style license is friendlier to companies who may want to do something with your code, and, if they're smart, maybe even contribute something back.
Open sourcing is a mixed bag. The sad fact is that open sourcing will generally limit the number of companies that will consider buying you by some substantial amount. Could probably get the poster a cushy job at google, though...
The idea was some sort of middle road between abandoning any hope of commercial success, and doing it 100% as a classic proprietary software business. I have no idea if it's feasible for his product though.
That said, if you really just 'give up' any commercial hopes, a BSD style license is friendlier to companies who may want to do something with your code, and, if they're smart, maybe even contribute something back.