Well not sure how the digbit admin correlates chrome with attackers but here is hes explaination for chrome user-agent not working:
Yes, it only limit chrome Chrome/13.0.782.109, because attack are using this.
Easy, he is associating chrome with the attackers because we are the attackers. The stat check system in bh is being mistaken as DDOS attacks by many of the pools. BitMinerUnion moved over today because of DDOS attacks, and I'm sure it was us