As one of my few social accomplishments is to be able to recite "The
Shooting of Dan McGrew" in its entirety, I guess I may put in my two cents
worth here. I don't see any evidence that the piano on the Malamute Saloon
was a player.
I think there is evidence that it wasn't.

After the stranger comes into the saloon and shouts drinks for everybody,
the poem goes (more or less),

"His eyes went rubbering round the room and he seemed in a kind of daze,"
"'Til at last that old piano fell in the way of his wandering gaze."
"The ragtime kid was having a drink; there was noone else at the stool,"
"So the stranger stumbles across the room and flops down  there, like a fool."
"In a buckskin shirt that was glazed with dirt he sat, and I saw him sway,"
"Then he clutched the keys in his talon hands.  My God, but that man
could play!"

So, the poem says the piano was a piano. When the pianist took a break
nobody else had a go, and I can't see that happening if the instrument was a
player.
Finally the stranger played the piano; he didn't clutch the levers in his
talon hands.

And anyway, wasn't "box" commonly used by jazz musicians as a slang term for
a piano?

By the way I believe that the Queen Mother can recite The Shooting of Dan
McGrew too.  I wonder if she knows the dirty version?  I wish I did.

John Phillips.