Apples advice is that the best place to run anything in Disk Utility is from the startup volume. That's not possible for certain things like disk repairs however it's still true for permissions repairs (as you will be using the most up to date settings).
Make sure you run the repair from an Admin (not standard) user account, preferable the first account that was set up on the Mac.
In any case the SUID message can be safely ignored.
See
this Apple support article.
The entry you have is the ninth one on the list. Scroll right to the bottom of the page for Apples advice.
