But you're right, on the ones where you can, Guard Point gets massacred by counter cancel. Overall, counters > guard points. The hard part of this match up is dealing with Bang's pressure responsibly (IE not mash 6/2D, use smart IB counter, block correctly when nothing else is available), dealing with FRKZ (Haku's lack of mobility hurts him bad if FRKZ gets in on him, so if your opponent FRKZ's try to use that Haku "RAAGH" jC zoning game) and just generally understanding where Bang shines/struggles (Shines on mixup/pressure/damage, struggles on defense and his pressure is gimped largely by counters) and where Hakumen shines/struggles in this matchup (Hakumen's zoning works well, bang's projectiles can and should be cut when possible, countered when not, Hakumen may have difficulty against a bang that understands how to utilize dash grab tactics, so get good at teching throws and not getting throw countered)
Also, on Bang wakeup, if he has 50 meter and likes throwing ashura as a reversal, if you block on his wakeup and 2A shortly after he has had opportunity to do things, you option select punish a quick ashura or put him in block stun.