Do anthropologists think this way?

Well I'm not sure it is the opposite. An anthropologist is within a group of people to observe and learn about them, while a missionary is there specifically to try and convert people to their religion. Some missionary groups are more forceful in how they go about things and others tend to be helpful with the hopes of converting through kindness. Keep in mind that providing some goods to other cultures quickens the influence of that culture regardless of much they "preach". As for anthropologist, the argument can be made that they are doing something to the culture they are observing simply by being present, but in this case they try not to influence the culture by instilling their views of say right and wrong into that culture.