Should I be concerned my 9 y/o grandson's favourite song is named I hope You Die In a Fire?

I think so. Kids will grasp whatever gets a rise out of adults, for attention.
Keeping a wary eye open for further manifestations might warrant
acknowledging the concern to his parents.

It's amazing how big business will rally behind the constitution
and stress freedom of expression. Let someone direct somewhat
the same rhetoric at the producers of toys like that, and the
argument shifts towards other constitutional rights

Here are the lyrics,

I really hate you
Stop getting in my way

I've lost my patience
When are you gonna decay?

I want to throw you out
Just like my broken TV

If you'll come back once more
It shall be painful you'll see!
]

I hope you die in a fire!

Hope you'll be stabbed in the heart, hope you'll get shot and expire!

Hope you'll be taken apart

Hope this is what you desire!

It's almost over
Why can't you just let it fly?

Don't be afraid
It's not the first time you'll die

Your mechanical parts click
Sounds like when I broke your bones

Once I get my second chance
I won't leave you alone!

Oh yeah!

I hope you die in a fire!

Hope you'll be stabbed in the heart, hope you'll get shot and expire!

Hope you'll be taken apart

I hope you die in a fire!

Hope you'll be stabbed in the heart, hope you'll get shot and expire!

Hope you'll be taken apart

Hope this is what you desire!