New one on me. While that could have been done, or maybe even was, I am pretty sure the sight guards were put there to protect the sight blade from damage, not as an aiming point for a running enemy soldier.
FWIW, the early M1 rifle, of WWII fame, originally had front sight guards that were almost straight. Then it was found that too many soldiers were mistaking one or the other guard for the front sight blade, so the guards on both the M1 rifle and M1 carbine were given a greater outward bend.
Jim