Indeed "historical Palestine" does seem like a slight of hand. It claims to be a simple reference to an area of land, while strongly playing a lip service to the claims of Palestinians to all of the land of the geographic Palestine. As This sentiment is far from uncommon. Here it is, for example, expressed in this elaborate tweet:
As such, it plays into the narrative that Israel doesn't have a right to exist.
I think the term "geographic Palestine" would serve the purpose of referencing the area under the discussion, without enabling what is essentially a dog whistle for denying Israel's right to exist.