The SNP took a Majority at Holyrood in 2011 and have held it since. Stirling-Alloa and Airdrie-Bathgate were before the SNP Majority, and Borders railway got authorisation before the SNP took full control but the SNP were the ones who delivered it, alongside the improvements to Perth-Inverness, Aberdeen-Inverness, several New stations and an electrification strategy that is steadily delivering a pretty comprehensive network.What goes on North of the border is North of the border. Just pointing out some similarities !
Also, being a Conservative or not goes far beyond rail policy. Whatever else you might think of them (and I would never vote for the SNP), they are definitely not 'conservative' in their approach to the state, governing, social issues, and many other policy areas.