Big Boss Man- Singing as PCA?

An oldie, but a goodie, this week's labor related song of the week is Big Boss Man. It's a blues song sung by many (Elvis Presley and the Grateful Dead among them), but first recorded by Jimmy Reed. The song is a complaint directed at a hard-driving boss. Even though the singer is complaining about terms and conditions of employment (working hours, breaks, lack of help), the singer's complaint is likely unprotected under the NLRA as the song seems to only be about his own personal issues and not about group concerns. Now, if two or more employees were singing this song together they could be cooking with gas, although maybe they'd just be griping.  

With singing on picket lines and the long history of the NLRA, you have got to figure there are a bunch of cases on singing as protected activity. But I only know of two. There is Tribune Publishing Co. (N.L.R.B. Div. of Judges 2001) where the judge concluded despite the respondent's concession ("By singing the union's name so that employees could hear him, Alger was arguably engaged in union activity. By singing in a voice to bolster the spirits of his co-workers, Alger was arguably engaged in concerted activity."), that a union steward singing a ballad with union lyrics was merely seeking attention and not engaged in protected concerted activity. And then there is MGM Grand Hotel, 275 NLRB 1015 (1985) where the discriminatee's termination was unlawful where others weren't really harassing employees with their "scab song". Are there more singing cases out there?

 Here are the lyrics and the Jimmy Reed version

Big boss man
Can you hear me when I call
Big boss man
Can you hear me when I call
Oh, you ain‘t so big
You‘re just tall, that's all

You got me working, boss man
Working 'round the clock
I want me a drink of water
You won't let me stop
You big boss man
Can you hear me when I call?
Oh, you ain't so big
You just tall, that's all

Gonna get myself a boss man
One gonna treat me right
Work me hard in the day time
But I'll sure rest easy at night (Grateful Dead lyrics vary slightly)
Big boss man
Can you hear me when I call?
Oh, you ain‘t so big
You just tall, that‘s all