Joe,
You really don't NEED the security of a holder like that for the Drop Zone if that's what it's clipping do you?.......The Drop Zone has a pretty good containment reach correct?

What I do on my drop aways, is simply use Moleskin........roll up (2) 1/2" pieces sticky side out and place them on the riser parallel to the direction of the arrow about 1/2" apart, then cover those with a piece for the whole front half of the arrow shelf.....make sure to fit the moleskin down in between the 2 stuck on pieces.
This makes a nice low profile arrow guide and no chance of hitting it anywhere.