Many other interesting things in that presentation, of course (in particular about the sea-change which occurred when the FCC relaxed their regulations for RF interference, and the hazards of falling the wrong side of that line.) If you have a subscription, you can read a similar written account in
Encore: Atari's Second System, where a similar aside appears:
Quote:
The Atari VCS used a modified MOS 6502 CPU, and the same CPU was chosen for the Atari PCS. During the development process, Atari considered a 16-b extension of the design, tentatively called a “6509.” It would have a 16-b accumulator, two 16-b index registers, a 16-b stack pointer, and a zero page pointer. After consideration, Atari decided not to risk the development schedule any further, since it was already committed to more than one ASIC for I/O. However, the “6509” design became the “65816,” used in later Apple II-family models.
There's also a freely-available article
Champions In Our Midst about the 2600 design. Particularly interesting for the background to the selection of the 6502.