WhatsApp got that hassle because it failed open and didn't clearly inform the user that it was doing so.

If the user is informed they have a non genuine device that is not safe or secure (e.g. like Windows' nag notification), then they can't expect it to work like a secure device, but more like an ordinary phone.

Then both normal consumers (who will continue to use the phone since they didn't really care too much in the first place about safety) and security conscious consumers (who will re-buy asap) would be more inclined to use the same brand in the future