Common wisdom is that Quicksort is slower than insertion sort for small inputs. Therefore many implementations switch to insertion sort at some threshold.
There is a reference to this practice in the Wikipedia page on Quicksort.
Here's an example of commercial mergesort code that switches to insertion sort for small inputs. Here the threshold is 7.
The "brute force" almost certainly refers to the fact that the code here is using the same practice: insertion sort followed by picking the middle element(s) for the median.
However I've found in practice that the common wisdom is not generally true. When I've run benchmarks, the switch has either very little positive effect or negative. That was for Quicksort. In the Parition algorithm, it's more likely ot be negative because one side of the partition is thrown away at each step, so there is less time spent on small inputs. This is verified in @Dennis's response to this SO question.