Alko Hitch Lock

I have always locked my caravan to the car on journeys using my Alko Hitch lock but was recently told, by a fellow camper, that I shouldn't' do this in case the emergency services needed to separate the car from the caravan quickly in the event of an accident.

Whilst I am sure it was a requirement from my previous insurance company when the vehicle was left un-attended on a journey, say at a service station does anyone know the correct answer ?  

Thanks