The location of Stations on the rail network is a matter for Iarnród Éireann.
The company informs me that the village of Rathwire has a modest population and Iarnród Éireann is not aware of any plans for major expansion. A new station would therefore be totally reliant on park and ride business and these customers already have alternative options at Kilcock, Enfield and Maynooth. Any new station on the line between Mullingar and Maynooth would need to be justified on the basis of substantial proposed development in the locality and supported by developers accordingly.