Spoke with my Service Team Leader yesterday (01/19). He tells me one of his Techs did some research on this question and found that the rear window button on the remote can be disabled. The Tech also said the only way to know what all the programming options are for this button is to bring my 4Runner in so they can plug their scan tool into it. Once the scan tool is plugged in the Tech should be able to see all the programming options. I was also told that programming can be different for the same model vehicle of different model years.
The Service Team Leader told me that since I purchased my 4Runner from their dealership and since it was the first programming change (from factory settings) the programming change would be No Charge. He suggested I have it done at my 5K service.
So, it looks like the answer to this question may take a while for me to find out (Iam just shy of 2K miles). If someone else here is taking their 4Runner in for scheduled service they might want to ask about this reprogramming if it is also an concern for them.