That's the goal! From what i've heard, the EU won't accept that as a valid reason, as they have already agreed a deal to thatgoal. WE have to come up with a better option to make the extension negotiations plausible otherwise what's the point of the extension?
Everyone seems to be agreed that In the (to my mind somewhat improbable) event that Jeremy Corbyn gets his General Election and Labour go on to form the next government, the EU 27 would be minded to grant an extension to A50 even though, going by what some members of the shadow cabinet have said recently, Corbyn's goals for the negotiation would be as impossible as anything Boris Johnson ever dreamed up.
If the EU27 would be prepared to grant an extension for what would clearly be a waste of time -- since eventually Corbyn would have to come back to Parliament with a very different Withdrawal Agreement from what he was seeking --- why should they not be minded to grant an extension with a view not to prolonging negotiations but to giving the UK time to decide how best to resolve the situation, thus avoiding the no-deal outcome that no sane person wants?
I don't expect any request for an extension to come immediately -- first I expect the EU 27 to make it clear, yet again, that the Withdrawal Agreement isn't up for renegotiation, unless maybe the "red lines" change dramatically, though the the UK's subsequent relationship with the EU would be, and to wait for that to get through the heads of the Conservative Brexiteers.
Eventually, I hope it's going to become clear to Jeremy Corbyn that he's not going to get his election and to the Conservatives that they're not going to be able to renegotiate anything in the WA, and that the only sane choices are ratify the WA or Remain. However, there's no parliamentary majority for either option, so the only way out of the impasse is to organise a referendum to resolve the issue. That would mean passing legislation to give force to the WA if confirmed by a referendum and otherwise cancel A50.
But although that's the only workable solution I can see to this mess, it's going to take time for the two main parties to come round to accepting that. And then the necessary legislation and other arrangements are going to take the best part of a year to set up. However, the disadvantages of delaying to enable that to happen are nowhere near as great as those associated with crashing out with no deal, which would be seriously bad news not just for the UK but for the EU and the rest of the world economy.
Delay, not to allow more time-wasting negotiations but to give the UK time to come to its senses, seems to me by far the least bad option for everyone.