Is RIT Necessary?

Thinking a bit more deeply about Murphy’s relationship to Pruss, it now seems to me that RIT is not necessary for a Pruss-style argument.  To see this, here’s a proposal for how a Murphy-style and Pruss-style argumentative framework against homosexual activity may (very broadly) go:

Murphy-Style Argument: 
1. Marriage is an aspect of human flourishing
        (Discoverable via theoretical reasoning)
2. We are obligated to not undermine aspects of human flourishing.
        (RIT)
3. Homosexuality undermines marriage and is not itself an aspect of flourishing.
(Theoretical reason?)
C1. So homosexual behavior is wrong.

vs.

Pruss-Style Argument:
4.  We should love everything appropriately.
(Intuitively known norm?)
5.  What counts as appropriate depends upon the nature of the patient
(Theoretical reason and the definition of love--union and goodwill)
6.  Homosexual behavior is inappropriate given human nature.
(Theoretical reason)
C2.  So homosexual behavior is immoral as it violates the norm to love everything appropriately.

Premise (2.) seems reliant on a RIT sort of move, or at least seems best supported by a RIT sort of move.  Aspects of human flourishing provide us with normative reasons to promote and pursue them.  But it doesn’t seem to me that Pruss’s argument needs RIT.  Which premise would depend upon it? (perhaps premise (5.)--more below) These two argumentative styles diverge on the source of normativity.  Do the goods themselves generate normative reasons to pursue them?  Or does a master rule, like the norm to love everything, give them their normative power?  I think Murphy’s argument falls more in line with the former, and Pruss’s with the latter.   (It's not even clear that these two approaches are opposed to one another in terms of ontology. The different styles could be reflective of merely an argumentative strategy.)

Premise (5.) best mirrors the more classical style of argument given by Murphy.  Still, I think it can work on a weaker principle than RIT, which I’ll call the Combination Principle.

Combination Principle:  It’s possible for an action that would otherwise be morally insignificant to gain moral significance in light of the nature of some agent P.  Imagine that P cannot make a statement of C-type without, from the necessity of P’s nature, subsequently lying.  C-type statements may not be wrong for any other types of agents other than P, but they are morally wrong for P in light of P’s nature.

Note: Values still have a place in the Pruss approach, they just aren’t playing the normative role they usually play in Natural Law.  We are to respond lovingly to the good, and this is how the goods exercise their normative force.