I wonder what a task looks like. They're supporting essentially adding a task to a machine every 2.5 seconds, which is a really high rate. It seems like most systems are built around slower resource reservation and then once resources have been reserved, they can pull from a queue for tasks assigned to it: E.g. Lambda: https://www.youtube.com/watch?v=xmacMfbrG28&t=123s
According to their paper 87% of the tasks live for less than 10 seconds. It sounds like they're solving a characteristically different problem than is solved by Borg.