As for me, I'll go with the Reasonable Person argument instead. Would a reasonable person expect that to vote in April, you must be registered by last October? No he would not expect that. Therefore, I am sympathetic to the iced-out voters here.
Notice that I'm not saying I'd excuse their mistake, but yes, I'd be very sympathetic.
I’m surprised they have that much cushion for their dropdead date, but glad. There will be enough questions with legitimacy and fraud in the current system. Imagine if they allowed you to register up to the last minute. Complete chaos.
That's not exactly the case. If you were not registered at all, you could register up until a few weeks ago. It was only party-switchers that had to make the change by October. And I am actually okay with that - it helps prevent an "Operation Chaos" type of situation, where you have a lot of people switching parties at the last minute to sabotage the other party by picking the weakest general election candidate.