It is a given that they are herbivorous scavengers; but, does anyone know if they will eat dead trees like the one referenced in the OP? Living in a place with lots of deer, I have never them strip something that has been felled. That could just be because they had many better options, though.
Unless your fir is sitting in a big pot of soil in your living room, it is essentially dead. It may be still green and wicking up liquid, but as soon as you put it outside it will dry out and/or start to rot. It is not like it will suddenly regenerate roots and live to next season. From the deer’s perspective it will be a dead tree.
My experience with planting coniferous saplings is that they love pines but will avoid spruce, which is why I only plant spruce now. End result is that the type of tree may make a difference. I am not sure if it the tree being “down” would matter or not.
Edited after looking at the OP closer, my experience is that deer like douglas fir as well.
We fall red cedar for the deer in the deep winter (like right now) they come running to the sound of the chain saws.
The loggers have deer all around them browsing the tops left behind.
Just this week reports were coming in that deer are eating Black Spruce. This is not a common occurance. They do eat Balsm Fir in winter. The old times would say that eating Balsm was a winter tonic.
It is next to impossable to grow red cedar trees around my hunting shack deer will chew through the nylon mesh. A 6’ fence is almost the only way to give a cedar a chance. I have been struggling to grow them around my sauna for years.