It's not possible to block bribing/intimidation from interface. The closest thing you can do is to have a custom line in "Bribe Success"/"Intimidate Success" topic with negative ModDisposition in the action box, something like "I'm taking your money and won't help you anyway, nyah nyah". But you have to keep in mind that bonus from bribing is random, so your penalty for must have be big enough to cover possible jackpots from high Speechcraft/Personality/Luck but at the same time reasonable enough to not be overkill to minimal bonuses.