Upvote:4
It doesn't seem so.
Earlier Egyptian temples in Nubia, for example the temple of Wadi al-Sabua, had been located within what appear to be fortified enclosures.
That does not appear to be the case with the Abu Simbel temples. This, in turn, suggests that by the time these temples were being built, they were considered to be safely within "Egyptian" territory, and did not require fortification.
A useful source here is Richard Wilkinson's The Complete Temples of Ancient Egypt.
This article on Egypt and Nubia describes the relations between the two countries over time, and details Egypt's military expansion into Nubia in the New Kingdom. It shows that Egypt's southern border was far to the south of Abu Simbel when the temples were constructed.