I don't think the mount would've made any difference.
Either the wrong fastener was on the clamp(s) that held the driveshaft in or it/they just weren't tight to start with.
Same thing with the bell housing, I've seen cars toss the rear of the driveshaft on the highway, the spinning shaft raises hell with the floor pan, but they don't break the bell housing, But I can see where it could if the fasteners weren't tightened correctly or enough.

fwiw, ymmv, mu point oh two.. etc. etc. etc.