It’s an interesting question, and this decision is groundless IMHO. (I hope somebody else will answer this thread if there is a legit reason behind this design decision).
Moreover, Google shows how to format those static initializers in their good practice formatting guide https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.8.3.1-array-initializers without saying anything about how bad it is to use those constructs …
I guess that the person behind that rule just had a tooth against that style of programming 🙂