As an aside, from a legal perspective, amicus briefs are nearly worthless as they usually just parrot what the plaintiffs already say. (In fact, some/many federal judges will not accept them for that reason.) Thus, Northwestern jumping on the Boston court bandwagon is just virtue signaling. (OTOH, it looks good on the CV of the law students who draft the friend of the court brief.)
Much better would be for Northwestern to join Chicago (and Michigan?) to file their own case in a Chicago District Court. If they could get a ‘local’ federal judge to give them a TRO, they are good-to-go for fall. (Doesn’t mean the TRO will not over turned by say spring, however, sending Internationals back home.)
Give them more than a few days to figure it out. They have numerous options and they just need to sort thru them.