The landlord might think that there is a higher chance of Twitter eventually paying ( through lawsuit or good will) than finding another tenant, or something. Which might be true, but is still a shitty move.
Nothing, they have initiated legal action. They should chain the doors shut. If musk wants people to work from the office he Reilly should oughta pay the rent.
Potential future value, lack of political will power on the end of those orgs they would need to assist (does the Sheriff want a picture carrying a Twitter bro out of his cube, etc).