EyeSight does indeed have low and high temperature limits programmed into it. It's even noted, more than once, in the EyeSight manual. The Factory Service Manual further states that EyeSight may enter Temporary Stop mode at temperatures above 70°C (158°F) or below -10°C (14°F).
Park your Outback, windows closed, in the sun on a hot summer day in any state along the southern border of the U.S. and the heat-soaked interior temperature (i.e. the temperature "felt" by the EyeSight camera module) can easily exceed that limit. I have personally experienced it several times in the desert southwest of Texas, New Mexico, and Arizona.
