Is it a standard procedure to use emergency slides without imminent danger? On 11 Jun 2017 Easyjet U23246 from Ljubljana to London Stansted diverted to Cologne-Bonn over a "suspicious conversation". All passengers were evacuated using the emergency slides, see BBC Video.

This made me wonder why this is appropriate at all: 


There was no imminent danger. It's an international airport, so surely they have at least one set of mobile stairs that could have been used in a safer manner?
Apparently nine people (of 151) needed medical attention after using the emergency slides. That's 5%!
If it had been an incident and police needed to enter the aircraft, wouldn't they arrive on mobile stairs anyway?
Apparently the airplane sat for 30min before evacuation anyway, so it wasn't even faster to use the slides.


I'm just wondering what prompted them to deploy the slides in the first place. I'm under the impression that they need to be replaced upon use and hurried evacuation didn't seem to be necessary in the first place.

As a passenger, I think a lot of people might get argumentative over not having stairs. Especially when small kids and disabled people (e.g. dependent on a wheelchair) are on-board. Not to speak of the economic and public relations impact...
If an evacuation is called for the quickest method must be used, in this case slides. No exceptions no questions. Passengers can complain after they are out but they are not given a chance to argue during the evacuation, force can be used to clear an argumentative passenger so that the other passengers can get out. The 30 minute delay was before the decision to evacuate, it has nothing to do with the actual evacuation. Full scale evacuations require no more than 90 seconds for the aircraft to be certified.

What the police need is completely irrelevant to the evacuation.  

Slides can be inspected, repacked, and reused, they are test deployed at regular D maintenance inspections.(maybe C as well. D is every 6 years C is every 2 years) Emergency doors are also routinely opened for testing.

A passenger needing medical attention could very well be nothing more than a stubbed toe, light scrape, or being out of breath.