The only thing I've used grips for is service drops, i.e. for coax or telephone that's "flown" in from a pole to the structure receiving the service.

I don't know what the job looked like, so I can only guess. If the riser portion was done in nothing but conduit, the I can see how 200 CAT6 cables running 75 feet vertically might want to "slump" or creep downward. The threat of that occurring though, would depend entirely on the way the cable was supported at the conduit exits.

I've also heard riser grips being used maintain a comfortable bend radius around a corners or at the entrance of a data cabinet.

My preference is to use trays, ladder or multiple Caddy type J-hooks and velcro, all of which are acceptable ways to handle these issues. I'll bet that's what you're accustomed to as well. Bottom line? Yeah, it sounds like it may have been a bit overkill. But since that's what the customer wants to brag about on the golf course, I wouldn't argue. Install it and bill accordingly.

"Press play and record at the same time" -- Tim Alberstein