As soon as your 1 day late you are in default. Most organizations however give noticed and plenty of time before filing law suits thus my question. The "news" here seems to be lacking any context, and I assume bad intentions on the part of NY Times and Bloomberg so...
The article is too vague on details, and I don't see the actual court filing readily accessible (bad journalists! always give a link to court filings!). But given the timeline and the wording, it seems likely to me that Twitter has not paid its rent for November or December--in other words, it's not one, but two missed payments. If that is indeed the case, then I do not find it all surprising that a lawsuit would be so aggressively filed after the second missed payment.
Even if not the case, Twitter has had very public issues which make it extremely likely that it is intentionally not paying the bills that are due. Thus, if the landlord wants to get its money, it either has to get Twitter to renegotiate its contract to one that it is willing to pay, or go to court to force Twitter to abide to the contract (including, potentially, invoking early termination clause). I don't know how much Twitter is behind on to this landlord, but the initial filing costs to the landlord are likely to be in the realm of a few thousand dollars, so it doesn't take much for it to be worth it to the landlord to sue pretty aggressively.
I found it here[1] on the SF court website. It looks like they didn't pay December rent, due on the 1st. They gave them 5 days notice on the 16th and by the 29th they still hadn't paid.
