Sound scary but when looking at the facts, it is probably reasonable.

Both the university, the court, and the lawyer seem to not raising any fuss yet, signaling that whatever this is, it likely all legal and severe enough to warrant absolute silence.

The employer was likely contacted far in advance for detail not available to the public, and very likely they complied and realized there are serious issues that can tarnish the university's reputation, so they erased his name from their payroll. This indicated court order and sufficient evidences for multiple parties to be concerned.

So... best guess? National security matter. Like it or not, espionage is a thing and under this administration, all foreigner, naturalized or not, are under extra scrutiny. And the US is not above applying stereotypes.