The theme incorrectly looks at screen resolution to determine if the mobile menu should be used. That is not correct UX development. It should use the user agent string and display the mobile menu for all mobile devices. This is the correct way because it acknowledges a tablet/phone’s inability to hover regardless of screen resolution.
The site is unusable on non-iOS tablets because of this bug. Arguably, the iOS setting is a bit of a hack, too. When you enable it, the hamburger menu slides to the middle of the page. A place where nobody will think to look for it.