Hitch locks while moving?

I have an Alko Security device that fits over my AKS 2004 / 3004 stabiliser.  The bumpf from Alko says it can remain fitted while travelling.  Took the 'van in for a service recently and the Technician said take it off when travelling, but put it on when parked up.

Any idea who is right?

I've used it when travelling for the last five years, am I asking for trouble?

Thanks.

Peter