Did you end up taking the bracket off? I just ran into the same problem.

 

Took it off my "16" years ago, I have the tailgate step and nothing with the step engaged the bracket, local dealer didn't know what it was for after looking it up.

 

There have been a few threads here about it. Some members suspected this aided with proper alignment of the torsion bar when reinstalling the tailgate.

 

I took mine off as it made it almost impossible to take the tail gate off. It seems to be only for allignment side to side.
I take my tail gate off every summer for firewood and put it back on in the fall. I have a 2018 long box XLT 3.5.