The 'S' models are relatively rare because they didn't sell well enough to continue production after a few years.
There still is a niche market for them, but it's just that: a small percentage of the whole new and used Rick market.
It's not like it's a 1964 RM bass or something really rare.
The routing could be covered up by select stock RIC hardware, with the exception of the battery box, but that's on the back. The original 'guard is unmodified.
Not to mention that the guy has thought about this for several years, it's well planned out and carefully crafted, not just a spur of the moment weekend project resulting from boredom, soon to be regretted.
Sure, resale value is now reduced considerably, but I get the impression that's the last thing on the his mind.
If I was bent on pursuing this mod, I'd probably even change out the bridge. Put a black ABM or something on it.
The object is playability, and while I personally have very few issues with the stock unit, we can all agree, purists included, the stock RIC bridge is less than ideal.