Reading from pretty much the same sources: I vote for something in between.
In order for the Hiver psychohistory to work (even it if doesn't work as advertized), the need to take a very long view of history. And the very long view of future history seems to indicate that the Virus is a new lifeform which isn't going to go away. It's evolving at a very fast rate currently, but will settle into a stable state. Then, like all intelligent life forms, look to expand it's sphere of influence. And the virii have and can control enormous industrial productivity. The fear is if the Virus stablizes into a xenophobic/aggressive state it could sweep out and kill all life forms (in particular the Federation). Making friends with the RC allows the humans to build a strong empire to allow negotiation from a position of strength.
The other point is maintaining a very high technology, partiularly across a large interstellar empire, requires an enormous investment of resources. So much so the Hiver have strained the limits of Federation to support it, to the point of sacrificing their military capability. The hivers are afraid if the Virus gets orginzed and uppity, or the K'kree get aggressive again, or the RC turns hostile, the shift of resources to producing for a war effort may well collapse the Federation economy.
The Virius is a wild card and too scattered to work with. The K'kree are mortal enemies only cabable of "not attacking right now". However, the RC can be a source of raw materials and services, a market for goods, and a way to expand the Federation economic base. The same reason why the Hiver were so interested in the trade deal with Margret during the Rebellion, after the Solomani went all "Humans only" on them.
And there's a large group of Hiver for whom the mothering instinct has been aroused. The poor humans, all beaten up and bruised need a helping hand from the friendly Hiver.
So it is a genuine friendship the Hiver are offering, but it give the Hiver something much more important that the RC can imagine.