Taken literally, "Mooses" could be interpreted as a poem about the potential violence in nature and more specifically, the indifference of the natural world. The moose, from a human perspective, is closer to nature (than humans). Humans would think that he should feel at home in his natural environment, but who's to say that even animals in their natural habitat do not, at some point, feel out of place? Similarly, people that appear happy might also feel abandoned or alone: like the moose.
Taken as a symbol for the human individual, the moose represents the same feelings of being out of place in an indifferent world: the natural world and the cultural/social world. In this sense, the moose and/or individual person feels out of place, has no place - and this is illustrated in the first line. He is a "walking house frame." A house frame is meant to be sturdy, set in place, in its right place. It is firm and secure. The moose, however, is wandering, "goofy" and clumsily crashing into things. He is looking for meaning, with his antlers (thoughts) reaching up like hands to catch some/any meaning from heaven. Like a rootless house frame, he wonders where he belongs. Not only is he out of touch with nature, he is also out of touch with culture - his social world. When he meets the other moose, he doesn't make a social connection; he considers it a mirror - a reflection of himself or just another hopeless moose.
Allegorically (like a fable), this poem is about searching for identity (in nature and culture) and meaning. The meaning of the poem is the search for meaning. It is quite negative and sad; but consider that the moose's negativity is what might be preventing him from finding meaning. It could be a general statement on loneliness and/or a point about mental illness and depression.