I think people misunderstand what the "one of us" banner really meant
When the term "us" was used, it didn't necessarily mean in the context "He's an Evertonian like we are"
The "us" was more to do with Baines speaking out and telling the truth, whilst also saying what a lot of fans at the time were saying
He essentially gave "us" a voice at a time when we were voiceless and thus became one of "us" in the process
He didn't say anything that wasn't true, and Martinez's vindictive response to someone coming out and saying what fans were thinking was probably a moment where a lot of people who were erring about him finally started to turn on him
In a lot of ways, I see Baines as a genuine hero. His sacrifice started the ball rolling to Martinez's demise and essentially rescued the club from the eventual relegation we would have suffered had Martinez remained in power
So he truly was "one of us", regardless of who he supported in his youth