You can't conclude that by thinking alone; some experiments are necessary.
True, an electron in an electride is kinda "free", in that it isn't connected to any particular atom. But that doesn't mean it can roam the entire structure, free as the wind. In fact, it sits in a potential well formed by the neighboring ions and molecules, only the well is so wide and shallow that it looks more like a puddle. To decide the conductivity question, you want to know how one puddle relates to the others, and the answer may be any of the following:
- connected to form a continuous sea, much like in a metal;
- connected to form a network of channels;
- isolated but still close enough for electrons to tunnel between them;
- isolated and spaced wide apart.
All in all, theoretically an electride can be anything from a metallic conductor to an insulator, depending on its composition and structure.