Superb description, LeftEars. Pontinen has the right feeling for this gesture but the overall rhythm in the BIS recording is ever so slightly muddy at this critical entry. Am going to order the Ashkenazy.
It's an exceptional formal design as the movement starts out like a symphonic theme and variations, then the piano enters as an accompanist, then POW the movement becomes a dramatic piano concerto and, finally, the reversion back to the opening theme.
Have noted this formal experimentation with other symphonies by Scriabin to his credit. Did you enjoy the piano bass notes at the ending?