It looks so far like we have a winner!
For the purposes of part 95, a "station" is defined as "Any transmitter, with or without an incorporated antenna or receiver, which is certified by the FCC to be operated in one or more of the Personal Radio Services.
So, when we plug that definition back in...
Any transmitter, with or without an incorporated antenna or receiver, which is certified by the FCC to be operated in one or more of the Personal Radio Services is prohibited from communicating messages (except emergency messages) to any station in the Amateur Radio Service.
So, a more logical interpretation of the regulation yields a prohibition on the equipment communicating a message; presumed on its own and not focused on the person. In the back of my mind, there is still a little wiggle room until "communicate" and "message" are defined by regulation; when a station transmits under a person's control, a message from amateur service to GMRS, is the station still a station "certified by the FCC to be operated in one or more of the Personal Radio Services" when it is in the act of passing a message from one service to another? Or, is that a recursive reading of the prohibition? For example, FRS units are licensed by rule as long at they comply with part 95 (a) and (b). However, the minute the radio has a removable antenna, is frequency agile outside of channels, exceeds bandwidth, exceeds power, etc, it is no longer "certified by the FCC to be operated in one or more of the Personal Radio Services." Likewise, when a GMRS station is used to transmit a message from an amateur station or a GMRS station, is the transmitting station still a certified GMRS station?
But, I believe that the station definition clears up the main, read most probable, prohibition.
Thank you, @SteveShannon. Hopefully, when I forget this in the years to come (happens all the time anymore with me), others will remind me that we all hashed it out and remind of the definition of station.