For apps that don't care about decorations, the toolkit is supposed to handle it. Inside Electron would be the safest place to implement a fallback for applications that don't care about decorations. That way you can be sure it will work on any window manager that doesn't provide decorations, not just GNOME... I don't want to retread more of the discussion that was in the github issue, but one way to do it is to have Electron hook into GTK and draw the GTK decorations, like Firefox does.

GNOME is an open source project, asking them to reconsider a position doesn't make sense -- the default response to every feature request is "no" unless someone volunteers to implement it. And honestly I see very little chance that the current GNOME volunteers are going to implement server side decorations in Wayland unless someone outside the project steps up to do the work. Maybe Canonical would pay for it? It's a major change for something that no GTK/GNOME apps would even use, and it wouldn't really benefit those small applications... they would still have to draw their own decorations to handle any other window manager that doesn't implement decorations, such as Weston.