hmm never hear nothing about that. Not sure if tge picture if the GPR you posted is dirt or not but I dont think so. Mine is ans has the same size bolts as the one you posted plus it is in between a saddle of aircraft aluminium the has them large fork bolts going thru the top clamp/yoke. So even if the two mount bolts come out its not going anywhere. Haven't seen them move in the 6000 plus miles its been on
Will continue testing
Oh and I was in contact with GPR when I was designing mine. At that discussion never came up. So I am not really concerned.