Actually, that interpretation isn’t quite correct. The 30-day reporting window you’re referring to applies to initial SEVIS data entry and student registration at the beginning of each term-things like confirming enrollment, course load, address, etc. That’s under 8 CFR § 214.3(g)(2) and (l)(2), which govern routine reporting timelines for active F-1/M-1 students.
But the April 16 DHS request to Harvard wasn't routine. It invoked 8 CFR § 214.3(g)(1), which covers ad hoc or investigative information requests by DHS. That section gives DHS broad power to request any time the records needed to assess a student’s compliance with immigration status.