I don't think it should be determinative, but it shouldn't be prohibited. The reality is that if the judge says you can't move with the child, she's going to be in that position anyway.
It's a relevant fact. For that matter, it's relevant to ask the non-moving parent whether they can move. One of the things we do know is that in a non-trivial number of cases, one parent gets to move and the other parent can actually follow. Obviously it depends very much on their personal circumstances.
I support the view of Professor Thompson, and that's in my brief as well.