2014 SE TRD rear sway bar installation problem

[NYC-SE]

After reading so many positive posts recommending it I bought a TRD rear sway bar. Read the install instructions and the various threads here and it seemed like it would be simple enough to do. Today I crawled under my car to install it and well...not so simple.

The forward hole or upper hole (NOT the shock mount hole) is already in use. I was unable to get a picture but it seems like some sort of lateral bump stop is installed there. That's the only possible purpose of this doohickey that I can figure out. There is no mention of this thing in the instructions and I can't even find it on any of the parts diagrams I was able to pull up online. Does anyone know what I am talking about? My car is an SE model, so I was thinking this might be something unique to the SE.

If there is anyone here who has installed a TRD rear bar on an SE I would love to hear how you dealt with it. Toyota went to the trouble of designing and installing this thing, they must have had a reason. I am reluctant to just discard it without knowing what that reason is and how it would affect things.

Thanks in advance.