Our son can be claimed as a dependent but was not. Does he get the exemption on his return?

Our college son made 40K in 2016. We provided more than half of his support.  He can be claimed as a dependent but we choose not to so he can get the exemption on his return.  When I checked yes for he can be claimed as a dependent and no for he was claimed, TurboTax did not show he got the exemption.  Is it because if someone can claim you then no matter he actually does claim you or not, you do not get the exemption on your return?