not even that. implementing this requirement could be a general work stoppage whenever the senior engineer is in all day meetings or on vacation

With a layout of 4 juniors, 5 intermediates, and 0-1 senior per team, putting all the changes through senior engineer review means you mostly wont be able to get CRs approved.

I guess it could result in forcing everyone who's sandbagging as intermediate instead of going to senior to have to get promoted?

In my experience, Claude and the juniors piloting it are usually receptive to quick feedback along the lines of "This is unreasonably hard to understand, please try refactoring it this way and let me know when it's cleaner".