I would trim it down to where you can see live wood (some greenish instead of brown/white wood)

New branches will grow. You can select a new leader later.

Which variety is this? Some are more cold hardier than others.

They should all be zone 3 or 4 trees. Planted in zone 4. Mixture of varieties.

Just seems like if it was covered in snow it lived but otherwise not. Maybe they get more hardy after the first year?

Looks like transplant issue,..a reason to plant in spring.
You can use the dead top to tie a new branch from below onto for your new leader, ..cut it off later in summer.

Hmm. Always figured autumn planting when dormant would allow them to get a head start in spring? They were bought bare root and dormant when planted and into frost and below freezing weather about 2 weeks after.

Fall planting is better for warmer zones. I would say if you are in zone 4 or lower, you risk it. I am in zone 6 but with the past two winters we had, fall planting would be iffy.