It's not inconceivable that someday you'll forget it's there and run the carriage into it driving the DI rod into the delicate works inside.
There are (at least) two ways to avoid such a tragedy.
1. Tap a hole into your aluminum holder for a screw and lock nut that can be extended such that the carriage will hit the screw before it destroys the DI.
2. If you have sufficient space, withdraw the body of the DI into the aluminum holder far enough so that when the carriage hits the holder the DI rod hasn't fully bottomed out. This is clearly the easiest but you may not have enough 'grab' on the DI if you do it. Give it a try.