Nominating Austin and Liz is the best idea at this point. That way, they'd be reliant on Julia winning POV.
If he nominates the twins, Austin is more likely to win POV, pull off Liz, and then the two of them would have majority to get out the renom (whether it's Vanessa or John)
Julia is less likely to get that clutch win. Liz and Austin have won a lot of comps #BB17