Buddy of mine had his Bonne peg fail at the bolt on a bike with only 7500 miles on it. New replacement peg, installed by Triumph dealer, failed again within 500 miles, at the same bolt shearing point. He states he never stood on the peg. That's a design flaw. He counts himself luck to not have been injured in these two events.
Your concerns over "stressing" the frame in a tip over are silly. The Scrambler has a much more robust foot peg setup than the bonneville and we don't hear of frame damage when they tip over.
Do you think that hitting a curb or a moving accident with an over-strengthened foot peg might bend the frame? How do you know beyond your speculation, opinion, or conjecture?
Did your buddy buy his bike new and did he ever tip his bike over or hit a curb with his foot peg? How about a previous owner? Is it possible that the dealer mechanic damaged the foot peg by over torquing the bolt?
Design flaw? Possible, but highly unlikely. You havenít considered a perfectly good design that was not manufactured or assembled correctly could be the cause. If you want to convincingly advance the idea of a design flaw you need to do the following:
Collect history of failed foot pegs.
Gather photo documentation of the fractured part with measurements.
Determine what testing should be done and protocol for analysis of the testing.
Include nondestructive testing like dye penetrant, X-ray, or ultrasonic to find crack-like discontinuities.
Perform visual and macroscopic examination of the fracture surface.
Have an electron microscope examination performed of the fracture surface to determine the fracture mode.
Perform metallurgical examination of etched and un-etched mounted samples of the fractured part to delineate the microstructure.
Have a chemical analysis done to determine the chemical make up of the fractured part.
Have mechanical testing done to determine the mechanical properties of the part like strength, elastic modulus, and elongation at the fracture point.
Have testing done on other non fractured parts to compare with the fractured parts.
An engineering and analysis report should be written that discusses failure mode, formation of inclusions and recommendations for design or manufacturing improvements.
You might want to get busy. There is a lot to do before a convincing case can be made that there is a design flaw in these foot pegs.