Well because I'd been reading and thinking so much about the shekhina as the dwelling place of God on earth and about how the shekhina and the glory of God were so closely related. I saw the transfiguration story with new eyes. Maybe the veil over my mind was lifted. This leads me to a different interpretation of Peter's comments. The view from the overlook may be majestic but the road beckons.
Most commentaries make a similar interpretation.
To me, it seems that Peter is very close to being on target. That somehow he's glimpsed the meaning of the ancient truth of the shekhina. For as Peter was still talking the cloud came and overshadowed them. The cloud which had been the symbol of the dwelling place of the Glory of God on earth overshadowed them. It's as if God provided the dwelling place Peter was talking about.