Hi Mark,
Thank you for using Syncfusion products.
The behavior of SelectionChanged event to get fired is when it switches from one item to another item. So, if there is a page/item available for navigation it will get switched calling the SelectionChanged event.
Based on your requirement it is needed to have a dummy page and the content of the page can be updated dynamically on switching handling the SelectionChanged event and you have achieved that correctly.
Please let us know if you have any concerns.
Regards,
Paul Anderson