largest Indian community in Scotland isn't in Edinburgh
Airport catchments do not really reflect endemic populations, if an airport is convenient and accessible and offers connections, direct or otherwise, they will use it.
This from RASCO highlights Scotland's central belt access times.
1-hour access time by road:
To Edinburgh Airport : 2,536m or 50.1% of the Scottish population
To Glasgow Airport : 1,982m or 39.2% of the Scottish population
To Prestwick Airport : 1,401m or 27.7% of the Scottish population
2-hour access by road:
To Edinburgh Airport : 4,01m or 79.2% of the Scottish population
To Glasgow Airport : 3,756m or 74.2% of the Scottish population
To Prestwick Airport : 3,407m or 67.3% of the Scottish population