It's a result of their weighted rating system and it being one the top 250 theatrical feature films... Rating is a bit out of whack for the controversial ones in the bottom top 250.
The formula for calculating the Top Rated 250 Titles gives a true Bayesian estimate:
weighted rating (WR) = (v ÷ (v+m)) × R + (m ÷ (v+m)) × C where:
R = average for the movie (mean) = (Rating)
v = number of votes for the movie = (votes)
m = minimum votes required to be listed in the Top 250
C = the mean vote across the whole report
for the Top 250, only votes from regular voters are considered.