Is this the idea that the left foot oblique is for right handed people and the right foot oblique is for left handed people to write with? Or is this some kind of other Parker terminology?
Yes, that’s the idea, in general usage. Parker official terminology would call the left-foot nib “Oblique” along with the line width (e.g. FO - Fine Oblique) and the right-foot oblique “Reverse Oblique” (e.g. Fine Reverse Oblique).
Just as an aside, these nibs are recommended for left or right handed writers but individual preference can vary. I’m left handed and I use both of them.