When the analogy is a worse thing than what is being likened, it is not trivialized. The thing being likened is moved to the level of the analogy and compared to see if the analogy is apt.
For example, "my teacher is a Nazi" does not make anyone think Nazis are only as bad as teachers, only that the student is overreacting (comparing the teacher to something that is on another level, i.e., worse.) The inverse, "Nazis were basically strict teachers," is a horrible thing to say as it brings Nazis down to the level of something benign.
To say The Big Bang Theory is blackface does not make a person wonder if blacks were actually only mistreated as much as nerds. It makes a person wonder if nerds are systemically exploited and mocked by social superiors. The answer is that in a very limited way, this happens, but it happens in an extremely irrelevant part of life (school) and nerds go on to run the world and are unquestionably full equals, possibly superiors, of more athletic people socially and politically. At no point here do we think blacks are only as mistreated as nerds.
On the other hand, saying something like "being black before the Civil Rights movement was like being the nerd in high school" is obviously offensive because we are bringing the black experience to the level of the analogy, being a nerd, and then making the comparison, and it's not even close.
For example, "my teacher is a Nazi" does not make anyone think Nazis are only as bad as teachers, only that the student is overreacting (comparing the teacher to something that is on another level, i.e., worse.) The inverse, "Nazis were basically strict teachers," is a horrible thing to say as it brings Nazis down to the level of something benign.
To say The Big Bang Theory is blackface does not make a person wonder if blacks were actually only mistreated as much as nerds. It makes a person wonder if nerds are systemically exploited and mocked by social superiors. The answer is that in a very limited way, this happens, but it happens in an extremely irrelevant part of life (school) and nerds go on to run the world and are unquestionably full equals, possibly superiors, of more athletic people socially and politically. At no point here do we think blacks are only as mistreated as nerds.
On the other hand, saying something like "being black before the Civil Rights movement was like being the nerd in high school" is obviously offensive because we are bringing the black experience to the level of the analogy, being a nerd, and then making the comparison, and it's not even close.