Mate - he's saying that the unbalanced weight of that setup will put far too much stress on the tripod mount on the grip. If you have a collar on the lens, you'll balance the weight and it will be safer.
That said, I'd consider an inexpensive strap as a safety strap - I'm not sure if Op/Tech is available to you in Croatia, but here is how I have my BR-7 set up:
(apologies for the evil Nikon hardware in the photos
)
http://enthusiastphotographer.files.wordpress.com/2011/12/br_fix.jpg
(ignore my Arca mount hardware)
Notice I attached the safety strap on the "buckle" area of the strap, not the carbiner. In the unlikely event that there is a failure, it will be the carbiner or the lock for the carbiner, so the strap is safe from either failure.
You could probably attach the other end of the safety strap to the standard strap mount of your camera on either side. There is a full write-up and links to the B&H store for the particular strap on my blog - the Op/Tech part number is 1301062 - B&H part number is OPSCUNL.