A No-Deal Brexit is the worst-of-all-worlds scenario
There is agreement on all sides that a no-deal Brexit would damage the country. Therefore, it need not be in the second referendum.
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In the fiasco that is Brexit, there is only one thing that politicians on all side of the political divide agree on: that leaving the EU without a deal would be of significant detrimental effect to the country. 
With that being said, the option to leave the EU without a deal should not be on the table. Also, if a no-deal option remains on the ballot with the option to remain in the EU, it would split the Brexiteer vote. This could result in a majority voting for Brexit but the Remain option winning out of the three. This would undermine the legitimacy of the second referendum. Therefore, there should be no No-Deal option on the ballot.
Politicians no longer agree that a no-deal departure would be the worst-case scenario. The deal The deal Theresa May bought back from Brussels was so flawed and missed so many of Brexit voters’ core concerns, that many in the Conservative party, including Jacob Rees-Mogg, would now prefer a no-deal Brexit to the one on offer in May’s deal.
Both sides of the political landscape agree that a no-deal would be the worst of the three scenarios. If it going to damage the country, and no politicians want it, it should not be included in a public vote. Therefore, a second referendum should be between May’s deal and to remain.
Rejecting the premises
Not all politicians believe a no-deal is the worst option now. Many now believe May’s deal is. Therefore, a no-deal Brexit should be on offer in a second referendum.