It turns out that back in March, the House passed a bill which included the following:
Sec. 535. (a) <<NOTE: China.>> None of the funds made available by this Act may be used for the National Aeronautics and Space Administration (NASA) or the Office of Science and Technology Policy (OSTP) to develop, design, plan, promulgate, implement, or execute a bilateral policy, program, order, or contract of any kind to participate, collaborate, or coordinate bilaterally in any way with China or any Chinese-owned company unless such activities are specifically authorized by a law enacted after the date of enactment of this Act. (b) <<NOTE: Applicability.>> The limitation in subsection (a) shall also apply to any funds used to effectuate the hosting of official Chinese visitors at facilities belonging to or utilized by NASA.
…because sharing scientific advancement is evil! Not only did that lead to a call for boycotting conferences by the international community, it turns out that even this ridiculous law was misread and led to non-official Chinese nationals being denied access to an upcoming NASA conference. Even after some public apologies – which seemed to have miraculously skirted media publicity – the shutdown may have jeopardized the visa approvals anyway.