Everyone can have their opinion on who ducked whom but as everything stands now-
Rousey is the UFC champ at 135 lbs, and i'm gonna go out on a limb and say easily the highest paid WMMA athlete, in the world's premier MMA org, getting SI cover shoots and movie roles(however you want to value those things) being promoted by the UFC which in turn promotes her brand (herself) in ways she could never do by herself.
Cyborg is not in contract with the UFC, and refuses to make weight to accept fights at 135 lbs, has been popped by an Athletic Commission for PED's, stripped of her title and suspended, is now signed with a much much smaller, lesser known, lesser paying MMA organization, is much less attractive (face it- this matters in WMMA popularity) with an idiot as a manager.
The ducking allegations are all in the PAST.
If we want to see them fight now- there is one way to do that- and Cyborg blew it by not accepting the UFC contract to fight in invicta at 145 and work on loosing the 10 lbs. to make the 135 limit to fight Rousey for the belt.
I dont see any other arguments that can be made to support other ways to make this fight happen unless you completely remove ALL business sense from the equation. ALL OF IT. UFC, Rousey as product, contracts, longevity, etc. Remove all of those and yes- we can argue all day about the ways in which this fight can happen.