[HP]

While in the shower I thought of a way to find a Nash Equilibrium

First, suppose BB calls with AKs some percentage of the time. Call it X
Now, write out the EV of SB pushing with AQs in terms of X
Set this EV equal to the EV of SB folding. Now you can solve for X.
So now SB is indifferent to pushing or folding AQs

After you have done this, now suppose SB pushes AQs some percentage of the time. Call it Y
Write out the EV of BB calling with AKs in terms of Y
Set this EV equal to the EV of BB folding. Now you can solve for Y.
So now BB is indifferent to calling or folding AKs

And now you have a Nash Equilibrium