Well that pic is better. It certainly appears to be a guide to keep the cables out of harms way. I assume (without seeing) the cables enter the downtube somewhere near the headtube. That doesn't address the issue with "stops." there has to be cable housing stops somewhere in the cable path, or it won't shift!

The guide appears to capture the cable housing. Is it just a short piece of housing or "noodle," or are the shifter housings full length? If so, you might not like the shift performance. Hopefully Redline can provide some insight.

I'd hope there's a stop where the housing enters the top tube- running bare cable through a guide captured by the "clamp" in your pic. For the front DR, only one stop would be required (where the cable enters the tube.) Rear DR requires two stops- one where it enters the tube, and one where the rear loop enters the chainstay.

If it's a full length cable, and going to the rear, a stop on/in the chainstay wouldn't be required. But, like I said you probably ain't gonna like the performance.