Maybe its the camera flash but that toy is 'yellowed' in a way I have never seen before - I am not sure if the problem is just due to standard yellowing as I have never seen an oranged Max before.
Typically the white just turns into a mustard color at maximum yellowing like the Scourge I photographed.
Kup, do you suspect something else is happening other than sunlight damage??
The damage on the FM looks like it occurred over a very long time.
This yellowed ratchet from thetf.net that you linked us, is almost as bad as that fort max on ebay.
I've also seen the grey plastics on a dinobot turned dark/dirty yellow, whilst the clear plastic turned dark orange (almost red) in colour. However, since i'm not the original owner, i cant say for sure if it was caused by only sunlight damage or another source.
thankfully these days, no one here is that neglectful to let our prized TFs yellow to a stage where it is too hard to reverse the damages.
To me that Ratchet's yellowing is different than the Max. That Ratchet has a similar form of yellowing as my Scourge, a mustard color while that Max looks a weird 'earth' orange color.
Clear plastic does turn orangy but not white plastic. White plastic turns yellow not orange red unless that Max is at a very severe rarely seen point of deterioration or its just the photo.
Grey plastic does indeed turn a dirty/green color but white discoloration is a pretty standard mustard yellow.