there’s nothing to stop it at all, BUT I doubt it will happen in practise. Chances are they’ve passed up the offer of VR to do so, and if they’re offered an early course, and turn it down; they leave the business. They’ll have gambled on the VR sum and lost. To make it work they’d have to stay in the CRS for the whole two years to even break even.
so, whilst there’s nothing to stop it, I just can’t see anyone taking that gamble.