But they are, Green says so. Quantum will work with the left or the right, they have no interest in politics, only money/power.
Actually, rewatching that scene, what he's saying is, We don't care who it is that's in power; we'll bribe them, threaten them, corrupt them, do whatever we have to do to put them under our thumb. You can sign our deal to give us control of Bolivia's water supply once we put you in power, or we'll kill you.
He's not saying that Quantum itself is both leftist and rightist; he's saying, they'll buy off or threaten any government, be it nominally leftist or rightist, so long as they get what they want. And meanwhile, their plot is one that's actually been used by real-life rightists.