You can only have one absolute moral principle; everything else must ultimately be contingent on not violating that core principle.
I am usually bringing this up on HN in the context of free speech, because I think free speech is a poor choice to make your absolute moral principle.
In this context, there's another example of a poor choice for an absolute principle.
Brotherhood, fraternity, loyalty to your group is frequently a good thing. Many things only work with trust.
But this is what it looks like when brotherhood -- loyalty to your fellow police officers, in this case -- is your absolute moral principle. Upholding the law and protecting the innocent come second to protecting your own.
https://en.wikipedia.org/wiki/Value_pluralism
And modern psychology and neuroscience appear to back it up.
"Absolute" is the key word.
But in the small we are always compromising on some things in favor of others. A principle can be upheld at great cost until it finally gives way. One principle can crumble away in favor of others very suddenly.