Context: the EoSD remake changed Cirno's "English beef" line, interpreted here as Cirno being a ⑨ and flubbing her line.

Daiyousei's panic may be because the UK BSE Outbreak was still prominent at the time of EoSD's original release, so Cirno would be at risk of mad cow disease. That also used to be one of the leading understandings of what Cirno's taunt was even supposed to mean, but ZUN says it's as meaningless as it sounds.