I wouldn't say "emulate", because a classical computer wouldn't be trying to solve it the same way as the quantum computer. The point (which would be amazing if true) is that a classical supercomputer would take 10,000 years to solve the same problem, no matter what method/algorithm it used.

For those that downvoted me, Scott Aaronson clarifies here that they do indeed mean simulate on a classical computer:

https://www.scottaaronson.com/blog/?p=4372

It's in the second paragraph.

"Our machine performed the target computation in 200 seconds, and from measurements in our experiment we determined that it would take the world’s fastest supercomputer 10,000 years to produce a similar output."