I modified the ebuild to make cdparanoia optional, since it has its own USE flag now.
Created attachment 46294 [details, diff] patch to add --disable-cdpar option Okay, well I tried to make a patch, but I failed miserably. I'm sure you get the idea though. :)
>since it has its own USE flag now Just for the sake of existence is not a good reason. There are exactly two ebuilds (mplayer and kdemultimedia), which have this _local_ use flag. And regarding the latter it's causing more trouble than it's worth it, so it's not unlikely to be removed again.
I have not been able to build a usable grip binary with it's cdparanoia support stripped out. It claims to support this, but becomes quite fragile. Closing this bug, having this USE-flag is not useful situation. Sorry.