You make it sound like that's some kind of get out of jail card. It's just a roundabout way saying that the UK will unilaterally break the agreement with the EU, and in doing so break the GFA. We've already established that you're a sociopath that doesn't care what that means for anyone that isn't you. But those of us that still have empathy regard the return to the Troubles as being a bad thing.
And if it's that easy, why haven't the Tories done it yet? For that matter, why bother signing up to the agreement in the first place?
My instincts say that this is just a desparate bluff, that the EU will never fall for. The problem is, it's Boris. And he's stupid enough to do something catastrophic either because he's too lazy to work to find a better way, or he's been so insulated from responsibility his whole life that he simply doesn't understand the concept of consequences.
So we'll see. But your "simple" solution is far from that.