So they could loot his body in a split second?Seriously now that NCR has 30+ guards its impossible to loot a player regardless if you are going to give his stuff back to him or not.
Don't stand near guards?Nah, that would be way too simple.
I think its those guards with snipers at NCR that take all the loot.The default ones run, but they are far and you have enough time to loot before they do