There are a few sit on the seat stabilisers which are a challenge to rig as securely as say a Tyler side mount.
The new ones draw attention from engineers as they are neither a hand held camera nor are they an approved item which is secured (from an engineers perspective) to the airframe.
Although the concept of a cameraman leaning out of a door holding a tethered camera is acceptable a 30 kilo apparatus that is top heavy and can usually only be secured at the base by straps, raises concerns with engineers.
On one hand it is safer for the operator to be well inboard operating a sit on the seat mount, rather than hand holding a camera near the open door.
On the other hand the top heavy sit on the seat mount is dependent upon adequate straps to prevent it swaying around in a heavy landing or something more serious.
A safer option is to install it on the floor but this often restricts the angle of view.
I wear a helmet when operating this type of kit in any moving vehicle.
I can't see any reason that they need to be certified anymore than the piece of string tethering the camera to the airframe when hand holding.
One eminent still photographer I know hand holds a very heavy DSLR with 600mm 35mm lens without as much as a strap.
Mickjoebill