I would not consider it a downside. When society labels an idea "offensive," it almost certainly biases people against that idea, so making people believe such ideas more would, on average, probably push them closer to the truth.
I'm not sure this is correct. Let us consider a toy model (emphasis in toy, which should be read as "baby-toy"):
There are three opinions: Center, Left and Right (C, L, R). Almost everyone believes C; positions on L are deemed offensive by people believing C and R, and likewise those on R by people on C and L. However, there is actually a 1/3 chance that the true position on any issue is on either of C, L or R. So there is a strong bias against "offensive" positions, as you say.
Now say you are on C and take the course, which gives you a...
From Julian Sanchez, a brilliant idea unlikely to be implemented: