So, your going to use an item near a flag to prevent the other team locking said flag.
I think this is already in the game...it's called a flag lock. 
Seriously though, I do get what your point is, but for my money i couldn't see it being used much. Id rather lock said flag and know its safe for a while. I guess there would be some limited use as you approach am enemy flag, cast the totem, prevent team from defensively locking it on you.
But then your carrying around Tele scrolls, cap locks, flag totems....what goes. HP pots? Wand of Speed?
.........