UPDATED: This is totally possible. I just was closing the host window before the async method completed. My interpretation was that the running context would persist, even i
Instead of using HtmlService.createTemplateFromFile you could use:
HtmlService.createTemplateFromFile
HtmlService.createHtmlOutputFromFile('simpleDialog');
Here you can find more information about this function https://developers.google.com/apps-script/guides/html/