The important part is the use of protected speech as probable cause to seek the warrant. If officers are shielded from accountability for illegally using protected speech as a basis for probable cause, then the lack of a warrant doesn't help Petersen.
> Novak established "protected speech cannot serve as the basis for probable cause."
It did not establish this; this was long standing case law, as the opinion points out. What it established was that police have qualified immunity from being sued for illegally using protected speech as probable cause if 'judges could “reasonably disagree”' about whether or not the speech is protected. In this case, if the PD can convince a judge that there was any room at all for 'reasonable disagreement' about whether or not a council rule that prohibits "derogatory statements or comments about any individual" is unconstitutional, then the PD will get let off the hook, even if the speech ends up being unambiguously protected. All that is needed is the 'reasonable disagreement' to immunize the officers, even if the conclusion is foregone.