Extortion.
Recent Supreme Court decisions have permitted the government to unilaterally cancel disbursements, even in flagrant violation of the plain text of law, impervious to preliminary injunctions, and then put up procedural hurdles to significantly increase the cost of reaching a final judgment in favor of the plaintiff. See, e.g., the most recent decisions issued this week in National Institutes of Health v. American Public Health Assn.: https://www.supremecourt.gov/opinions/relatingtoorders/24
So presumably the administration's deal was, give us what we ask for and you'll get the money Congress awarded, or don't and wait 1-2 years for any case to wind its way through the courts.