Far's I know, the OHK doesn't work on Bandits anyway, and I've attacked and killed plenty with the code on. Honestly, killing Bandits isn't a hard thing, just time-consuming.
I just keep a solid object between me and them, use range weapons, quickly attack once to aggro, then duck behind cover while they open fire, wait till they stop to relload, pop out, open fire and take out a chunk of health then duck back in to cover before I rinse and repeat. Takes 5 to 10 minutes to kill a couple. If you have a high health melee character, you can run around them in circles, keeping ahead of their cone of fire, and do a lot of damage too.
If you don't use the OHK .dll then you can also just use zombies as a shield, get a swarm around you, charge in close to Bandits and go to work, Bandits can hardly hit you since they hit the zombies more.