We have a lot of witch hazel growing in our mountains, and even with good deer populations, they don't get chewed much - if at all. No cages required from my experience. They make great understory cover to thicken the woods. They also grow well on woods edges.
As you said, they're multi-trunked. Bucks love to rub on those trunks here - with no bad effects to the whole cluster. The attraction that I see with deer - beside rubbing - is that once they get 8 or 10 ft. tall, and they get that "bending-over" look, deer seem to like to travel UNDER them and make scrapes UNDER them. I've used witch hazel clusters as a means of scouting areas for rubs and scrapes to get a handle on buck travels / populations. Deer seem to use witch hazel so much around our mountains, if I see a cluster of them - I'll go over to look for deer sign. Lots of rubs / rub scars & active (or old) scrape sites found under them. I have no idea why deer here have an attraction to them - for whatever reason.