The “elderly negro” at the SE 6th floor window 12:15-12:20 could be Eddie Piper IF he was wearing a red and green “plaid” shirt and IF he took off his glasses while he was hanging out the window. (Rowland would have seen the glasses if Piper was wearing them)
Mr Piper certainly is a viable candidate in terms of physical appearance (unlike Mr Williams). And I think the WC would have killed to make him the 'elderly Negro'.
However #1:
Is this Mr Piper (main picture)? The clothes look oddly uniform-like for someone with Mr Piper's role, but this man does look a ringer for Mr Piper:
If this is Mr Piper, then a bright plaid shirt ain't what he was wearing that day.
However #2:
If Mr Piper was the 'elderly Negro', then who were the two black people Mr Rowland saw in the fifth-floor easternmost pair of windows? Without Mr Piper available, we're down to Mr Williams and Mr Troy West. And the latter seems very unlikely. (Then again: perhaps we might need to revisit Mr Charles Givens' account[s!] of his movements in the minutes leading up to the assassination?)
BRW maybe went up to the 5th floor to eat his lunch about 12:05 erroneously thinking Norman and Jarman would join him immediately.
This scenario allows enough time for a 6th floor shooter hiding out on the 6th floor to place a box on the SE window ledge by 12:25 since Piper could have left the 6th floor by 12:21 returning to the 1st floor.
There is no conflict therefore fir the shooter having to of wait until 12:24 for BRW to leave the 6th floor since BRW was never there.
The chicken bones and Dr.Pepper on the 6th floor therefore either were left by Piper or placed there after the fact perhaps moved from BRWs speculative 5th floor eating spot.
I suspect the latter was the case.
But the key issue in all this IMO:
The sixth floor was a brilliant spot from which to view the P. Parade. The obvious spot for the manual workers. And yet not a single one of them chose to watch the P. Parade from there. Why not? It's bizarre---particularly when put beside Mr Williams' recollection that there was a general agreement among the sixth-floor crew to come back up to six and watch the P Parade from there.
Again, I suggest this was no stroke of luck for the assassination team. I believe at least one, but probably more than one, employee went up to six as their first choice but was told to leave the floor. They left that floor in the belief that it was being used for bona fide security purposes to keep an eye on the crowd from.
I believe the above would explain the two clusters of employees seen at those fifth-floor windows:
~12:15pm: two black people + (possibly) a white man (Mr Rowland's recollection)
12:30pm: Messrs Williams, Norman & Jarman
All of these people would have been innocent of involvement in the plot to kill Mr Kennedy