Good on the OP here! I have no problem with crossbows being used for deer. I've killed a couple of deer with a crossbow during Montana's rifle seasons and in weapons-restricted areas during the same time. I don't generally object to them, particularly as an effective tool for deer during rifle season. I do object to them being used during Montana's archery-only season on elk, for all kinds of reasons.
I disagree with Buzz. Despite the fact that contemporary compound bows shoot arrows at similar speeds to crossbow bolts, they require something crossbows don't: commitment and practice, and knowing when to draw. Even with 80% letoff, you can't hold a compound bow back forever. Many archery stalks are blown in the final moment of needing to draw, and that adds to the hunt. And people with fancy compounds spend far more time practicing. A crossbow takes all of an hour or two to be proficient out to pretty extreme ranges, which can also lead to unethical shots in the field. (Again, this is all in reference to elk hunting. The differences become more negligeable when you are sitting in a tree or a blind for deer).
As has been litigated multiple times in MT as well, the permit-to-modify archery equipment is the appropriate route to go down if drawing a bow is no longer a possibility due to injury or disability.