Ryan, this is, at least in part, a 2e:3.5e split.

In 3.5e all actions become GB base cost only (barring domain magic and a couple others) with RP then just modifying the success chance.

So the unblooded ruler can do all the same actions as a blooded ruler - although in effect being unblooded halves a regents the effective income as they have to use GB for base cost and also for boosting chances whereas a blooded rival could use RP for the latter freeing up gold for use elsewhere.

The 3.5e system seems better to me - although I disagree with GB costs for source actions - as the 3.5 e rules still give the blooded regent a major advantage in rulership, but a blooded regent is possible - under the 2e rules I wonder how holdings worked before Deismaar - was there simply no trade, law, etc, or more likely did bloodlines simply give the blooded a major boost in their attempts to control the holdings that already existed?

As for whether non-blooded regents could survive in Cerilia it all depends on how common bloodlines are, if bloodlines are few and far between unblooded regents can rule in the gaps.

Personally I'd make source actions have RP base costs only as they aren't open to non-blooded rulers and sources produce no income (under standard rules) making a mage regent beg and scrape for every action, not simply for realm spells.