IMO this is obviously a fault in the center software. Even if an airplane system did malfunction and send too much data, software is supposed to have built in "exception handling" for any reasonably conceivable error.

The most basic example of such an error is an attempt to divide anything by zero, which would crash the processor if not diverted.

A data overload (possibly an intentional Denial of Service attack) should be an obvious exception to plan for.

Even if the U2 malfunctioned, it shouldn't have shut down an ARTCC.