Why is there any debate about this? He has to do it. It’s only Tory pusillanimity that could stop it. If they vote against you to stymie Brexit then keeping them in the party means that an early election will be pointless. You could win, but if they’re still on-board then you’re back to the terrible situation you were in previously, and nothing has been gained.
Of course some of them could lose their seats anyway, even as Conservative candidates, due to a backlash from Leave voters, but that means you lose seats you could have won with a Leave candidate. It also shows you’re not serious about changing the Tories, and without change the party will die off. The early election may even be lost.
But most of all it’s a golden opportunity to get rid of these arseholes and to consign them into the wilderness forever. It’s a heaven-sent excuse to throw your enemies into the sea with no repercussions. Not kicking them out of the party would be like being in a war where you’ve driven the enemy to the edge of a cliff where they’re about to fall off, but instead of giving them a good kick to send them over you invite them back to your house for cocoa and biscuits, and you let them sleep over with all their knives and swords and flails while your lot are all sitting up writing with only pencils in your hands. ‘God has delivered them into my hands, and I have decided to … let them come back to my place to use my honing steel. And screw my wife and daughter. Because I want everyone to love me.’
Boris Johnson could possibly be this dim, but surely Dominic Cummings is not? Tory MPs are natural cowards, so a bastard can always beat them, if he can hold his nerve. (And if this results in an early election then… great!)