A cursory Google search returned 56 700 results, the majority referring to The Firebrand of Florence,
a Broadway operetta in two acts, written by Kurt Weill (music), Ira Gershwin (lyrics), and Edwin Justus Mayer and Gershwin, based on Mayer's play.
American Heritage Magazine refers to Samuel Adams as Firebrand of the Revolution
Oxford Dictionary Online, Cambridge, Collins, and Merriam-Webster dictionaries all have similar definitions for a firebrand,
A person who is very passionate about a particular cause
but don't use "about" or "of" with the word in any of their example sentences.
Even though usage of the word doesn't seem very common in the context you have given,
a firebrand of innovative content strategy
an innovative content stategy firebrand