A catchphrase to describe an over-protective subordinate

Solution 1:

Your question and descriptions would suggest that "lackey" is quite fitting. There are a variety of context dependent synonyms that also might be used.

https://www.thefreedictionary.com/lackey

https://www.freethesaurus.com/lackey

Solution 2:

“Brown-noser” and “suck-up” come to mind, but they are quite rude. And they require hyphens, which I don’t really appreciate. Can someone come up with a more neutral term, preferably non-hyphenated?

Solution 3:

A phrase that is often used of such situations is blind loyalty.

Her blind loyalty to the Dean makes reasonable discussion of these issues nearly impossible.

It doesn't necessarily involve aggressive verbal defense, but could.

Solution 4:

In the interest of using "something historical", let me exhort you to join the good fight to reclaim the original sense of Chauvinism:

Borrowed from French chauvinisme (“idealistic devotion to Napoleon”), named for Nicolas Chauvin, a legendary and excessively patriotic soldier of the French First Republic. The figure of Chauvin became especially famous as a character in the play La Cocarde Tricolore by the Cogniard brothers.

(Also, tangentially, I feel compelled to mention that I don't think "catchphrase" really applies here, but regardless.)