As a company, we naturally have limited resources. We wish we could develop full compatibility for all devices out there, but unfortunately we can't.
We're looking at the global market shares of Android devices, and GARMIN-ASUS is one of the least popular ones (even though we acknowledge that it is not a "bad" device, etc.)
I didn't say we would neglect it, I just said it might take sometime before we attend to test it fully. In the meanwhile, if indeed you know so many Viber users who are longing for full compatibility, you may gather them and jointly open many ticket to our support team. The more tickets, the bigger chances that we will prioritize this task
Here's the link to our support team: http://support.viber.com
A member of the Viber R&D Team, Viber Media Inc.