In a way that is a shame because it will cost about three times as much to build it next to a working line as next to an out of use one.Okehampton Parkway is a much longer term project and certainly would not be part of any 2021 reopening. The situation was simplified with the Dartmoor Rly going into administration - it was planned at one stage to have an interchange there and the Exeter service not serving the original Okehampton station. Sampford Courtenay station is nowhere near said village (or anywhere else for that matter) and in my view not worth reopening if it causes timing problems.
But with an "oven ready" station sitting there already equipped with inter city standard facilities, a big car park, and plenty of space for interchange with onward buses to Bude etc., it would be foolish to delay reopening for two years while that got built.