I'll wait to hear @andybons thoughts on this, but I'd say if we're going to treat "would ping more than 5 people" specially, it should just avoid doing anything.
I don't think it's viable to pick only a single person on the core team to always get pinged, and it may not be a trivial effort to add a rotation going just for these kinds of CLs. The safest thing is for gopherbot to say "welp, this is too hard for me to deal with, I'll tag it as no-owners and back out". Then humans can pick it up, just like all previous CLs before gopherbot did the reviewer assignments.
About 'no-owners' Tag
The no-owners is applied by gopherbot when it can't find an owner for the affected code. See CL
If no owners can be found, the tag 'no-owners' is added to the
change to prevent gopherbot from making unneeded API calls.