The argument is rational and reasonable. But be realistic. It has been since November, 2018 and the original license is not paid in full. What does that tell you combined with the company going dark?
Let me just add a bit of reality to contracts. I’ve had customers default several times on different portions of a contract. Do you jump to lawsuits right away? Hell, no! You talk to customer and find out why they failed to deliver a deliverable or payment and you work with them to make things right. Just because a contract is legally in default doesn’t necessarily mean things don’t work out to meet all deliverables and payments.