For me, the pure mortal template and bonus are one and the same, if you are not eligible for the pure mortal template, you are not eligible for the pure mortal bonus, since taking that template is what grants you the bonus and nothing else. If you want to make the pure mortal bonus a +2 power, go for it, but I don't like that solution one bit.
Like I said, to me it is not that you start with (at submerged) 12 refresh and loose 2 of them when you choose a power, you start with 10 and gain 2, if you choose the pure mortal template.