The Master's grades will not be in time, but the senior year's grades will be, which is what
the OP lacks if he applies now. There's also a risk associated with going straight for a PhD: one may flunk out if one is ill-prepared. Indeed one purpose (among many others) of doing a Master's degree is to reduce this risk.
I completely agree with you that a Master's degree is not the right thing for everybody. It just happens that many people on this board seem to be in a situation where having an MA might turn things around.
PS: I don't remember everything I learnt in corporate finance, but what other discount rate were you talking about? I was treating the stream of his future annual salaries as a perpetuity whose present value is salary divided by interest rate. Of course this is a simplifying assumption because he's not going to live "perpetually", but then again the possible increases in his salary (which were assumed away) could probably act as a counterbalance.