I recommend not smashing it into the ground as the best way to protect the camera.
Cant see that clip making a lot of difference, just moves the problem onto the next weakest link.
I bought one of these and its just a bit of extra insurance and could save you a lot of cash if you are unfortunate to have a crash .
I think taller landing legs would also be benificial .
That clip only protects the ribbon cable if the roll gimbal comes apart (and they do since the connection is just a press-fit compression). There is another piece (different manufacturer - but sold though Etsy) that bridges the bottom of the landing struts and prevents impact of the camera against ground-based projections (e.g., rocks).
There is no 100% protection. You crash you risk damage just like if you crash your car into a wall or a tree ;).
The retainer clip may prevent the Sensor shaft from pulling out completely at the roll axis sensor put it will not prevent the hole for the shaft in the housing to oval out and the shaft becoming lose. Furthermore the next item to break on the gimbal is the pitch axis sensor shaft. The pitch axis shaft will just snap and there is no retainer that can be put on that axis to prevent that. The ribbon cable will likely be damaged or you even can lose your camera head if that shaft snaps.