IIRC, moose can be pretty dangerous animals. On a few occasions I've heard they're responsible for more death and injury than bears and other 'commonly assumed to be dangerous' animals.

All in all, after seeing some pretty big animals out in the wild, I've given up the notion of carrying a .22lr, especially a single shot 22lr, as my only survival rifle. Animal attacks may be rare, but they aren't impossible....and somehow I doubt a .22lr is going to do anything stop or slow down an animal like that moose.