Please share where you have read that? Not disagreeing with you, and what you have stated very well could be the case.
On another forum (FTE) I started a thread on this issue and have been collecting data for MY22s and prior MYs, and some MY22s are reporting seat heat on RS and others, like myself, do not. It appears the high trim levels of MY22s are impacted. Ford's own Work Shop manual also describes when the heated/cooled seats will activate on a RS activation and I did not read anything that seems to suggest this is a safety issue and seat heat only engages when triggered by PTS/Key-on. If so, then why have specific RS menus items on IC menu for Climate Control=Auto or Last Used, and heated seat & wheel = Auto or Off. Makes no sense to me to have those RS menu settings then. Further my heated steering wheel does come on with a RS and prior to PTS/Key-on, so if this is a safety issue for seat heat, seems the same safety issue would apply to the heated steering wheel.
There is a member here on FT that responded to a thread about this, whereby he recently took his rig to dealer for service for this issue, and 4 Ford engineers looked at his rig for 2 days and determined that the HVAC module was not triggering/communicating with the heated seat module to turn on when RS. He was told that Ford engineering is aware of the issue and a "software" update will likely come in 2 months or so in the form of a TSB.