I am not against Osinbajo. He is eminently qualified to contest for the presidency if he so wishes. But ask yourself why the North, teleguided by the presidency/cabal, is rooting for him now? He was humiliated in the past by the cabal and kept in the inconsequential cooler before now. Why the sudden change of mind? Certainly not because of his intellect, impressive CV and urbane disposition. These qualities, while positive, mean nothing to the North.
More likely, Osinbajo is calculatedly seen by the North, as amenable to control and manipulation. He is a plan B. He will do as told and cannot and will not rock the boat in favour of any type of change of the status quo, of Fulani domination. He must have certainly learnt his lessons well. A repeat of the heady sack of Lawal Daura (former DSS DG) by Osinbajo, during his acting presidency, earned him severe punishment, including banishment from ever holding that position again. Osinbajo has no real experience in politics and no real political base, aside from whatever the presidency is allowing him to enjoy currently. The primary purpose of which is to stop Tinubu.
I doubt, that after that purpose has been achieved, Osinbajo will be needed. I also doubt that there will be a power shift to the South, if the North has its way. But in the event that the North is forced to respect the zoning agreement, Osinbajo as plan B, may suit their temporal plans for a lame duck southern presidency. This will be due to no fault of Osinbajo. He simply lacks the independence, political weight and network, experience, resolve and resources to do otherwise.
On the other hand, Tinubu despite his downsides and baggage, has the these exact qualities that unsettle the presidency/cabal and above all, make him a candidate difficult to control. He may rock the boat. He may begin an agenda to change the status quo, by using presidential powers to influence a drive towards restructuring in the National Assembly, through the promulgation of a new constitution. He may also eliminate or deal a decisive blow on Fulani bandits and terrorists, which PMB has not done. Conversely, Tinubu may not do any of these. But is the North willing to take its chances with Tinubu? I doubt it.
This in reality has led to the emergence of Osinbajo, not because of genuine love by the North or because of the SW itself, but because of entrenched Northern interests. Finally, you asked what is the goal of the SW? .That is not a difficult question to answer. In lieu of a Yoruba Nation, we want a fairer and more equitable country. We also want the Fulani terrorists stopped from their expansionist drive and insane bloodletting, particularly in the SW. Can Osinbajo guarantee or deliver on these? The answer is a definite no , not when the same north hands him power on a platter !