Did they say why they wanted the clearance lights to be disabled?
It has got to do with regulations here in the EU.
For instance: here in The Netherlands clearance lights on the front of a vehicle must be clear white and at the back they must be red. And since the front clearance lights on the front of Airstream Motorhomes originally are "orange" they officially may not be switched on while on a public road. Orange clearance lights are used over here in the EU as vehicles side markers.
Just like many other European Airstream-motorhome-owners I replaced the ICC-blink-switch with a toggle switch so I can easily switch off the clearance lights during the yearly inspection.
During trips, I leave the clearance lights on of course...I've never been pulled over....