Health & safety gone mad.
Nope, management probably already preparing for a personal injury caim for the broken ankle for a potential breach of a duty of care owed to the employee insofar as not ensuring safe access and egress to the place of work.
They may have been advised by their H&S adviser to refuse access until it could be made safe.
This was a foreseeable incident given the weather and forecasts, and possibly they failed to put measures (gritting) in place.
The person with the broken ankle could very easily have a lifestyle limiting injury all because the employer possibly didn't arrange for it to be gritted and checked periodically to ensure it was still safe.
So...in a nutshell, a management reaction to an incident and potential claim, a reportable injury tat could lead to a HSE investigation, all caused by mis-management.
NOT health and safety gone mad.
A simple and low cost measure has potentially caused loss of resource, insurance premium increase and a complete productivity loss for a day. MIS-MANAGEMENT