But there are other examples of musicians who could never duplicate their studio sound live, but nevertheless played on their original records: CHUCK BERRY and LITTLE RICHARD, to take two very famous examples!
Most blues-based or rock players do not copy their recorded solos 100% note-for-note when they play it live. The piano solo with octaves in YNCT is easily copied however...I do it almost note-for-note whenever Chuck does the tune because the crowd gets off on hearing it note-for-note...a highlight of the original cut. If in fact Johnnie had played the solo on the original, he'd have no trouble quoting it.
As you say the piano solo is easily copied and I am sure Johnnie would have had no trouble quoting it even if he had not recorded it. Maybe he simply did not want to play it or had forgotten about it. However your thesis could be right as well.
In case you wonder, whenever someone asks a question about Chuck's backing musicians on records, I usually base my replies on Fred Rothwell's extensive work. While some of his views may be debatable, he remains the No. 1 Chuck Berry discographer in my book.