Pathfinder is generally a more flexible system. Paladins are not stereotypical "refuse rewards, fight evil, be stupid, die". Their code of conduct depends on their god - paladin of Abadar (god of cities and merchants) should specifically ask for rewards, for example, as his god is basically a god of capitalism. Paladins of Irori (monk god, in short) had probably trained with monks half their lives.
The same is true with Thugs - a thug is a collection of abilities (frightening and brutal beating) that signify certain methods, not a villain archetype that you painted. It does not require you to be evil or do evil or dishonorable things (some classes or archetypes do, but not this one). It just means that your paladin relies on intimidation, sometimes supported by physical violence instead of just relying on physical violence. It actually makes sense if the paladin tries to achieve justice - a paladin may very well believe that some bruises and a healthy dose of fear can cause some bandit to reconsider his way of life and change for the better. Perhaps that paladin was even a bandit in the past (a common vocation in fantasy) and found the right way by receiving some. Often the alternative is to kill said bandits, which is hardly a less evil or more lawful option. Some might say that law works because it is supported by fear and punishment. You might also imagine said paladin as a "drill sergeant paladin," for example, going to a slightly different direction with this character.
Vivisectionist is far harder to justify though, which is why I did not try and instead had gone for the thug.