Questions about this aircraft:
Was the transponder an 8 key or a set and enter each number separately device?
How brightly was it lit?
I've had difficulty maintaining a steady altitude in good day VFR with an untrimmed aircraft while setting the code on a Trig. That was a code given as I left airfield frequency for regional ATC. Not trimmed for level nearing top of climb, below 1500'.
I busted the Class D, but quickly descended. 2,000+ hours solo, and flying my own aircraft. This accident was a rented aircraft.
I have much sympathy for the pilot. With the ATC transmission I doubt he would have been doing anything other than trying to fly.