http://www.ps3attitude.com/new/2009/02/killzone-2-bots-in-multiplayer-disabled/
Guerrilla have already spotted that a number of players have been setting up games where real players take on an army of low-end bots in order to increase their experience points artificially.
In response to this tactic, they released the following statement:
Were disabling the ability to add bots to online games as a temporary measure against rank-up abuse. A permanent solution is forthcoming.We welcome anything that stops people from being able to artificially unlock as many abilities as possible in a short space of time. Remember people, winnings are much better when youve earnt them