There's no proof or evidence at all of that. And most chemists agree it's the bromine used as a fire retardant oxidizing (hence different parts yellowing at different rates due to bromine ratios in plastic batches) not the plastic aging in any particular way (though very poorly treated plastic does become more brittle, it's not directly related to the yellowing)
Anecdotally I've been doing this in some capacity for 4 years, and the piece I did first (with the old method - expensive liquid peroxide), an NES dogbone controller, has been in constant use and is still as strong as it ever was, and hasn't re-yellowed either.
Happy to be proven wrong if you can prove it with backup from a plastics chemical expert commenting on the technique. But it's now an extremely widely used technique in retro computer circles.
EDIT: It's also not bleaching. It's mobilising the bromine, which has migrated to the surface and forms a stable complex with atmospheric oxygen.
Best write up I could find:
http://www.exisle.net/mb/index.php?...g-plastic-the-stain-isnt-permanent-after-all/