I also read it that way, but "What I'm about to say will be controversial, but bear with me for a second..." is probably a better alternative.
I think nowadays all the different types of disclaimers are all the same, and how receptive audiences are just depends on whether the audience read something similar or not 10 pages ago. It's weird.
Sure, but ironically a different kind of unintentional groupthink happens in this case. Some people read "I'm going to be downvoted" and...consciously or not...want to upvote it.
For another point of view, I personally appreciate the heads up that the opinion being voiced is believed to be unpopular so I can be careful to ensure conclusions I draw are informed ones since there are a variety of easy to make fallacies associated with unintentional groupthink.