Yep. May as well get a player. Clarkson is a good guy on and off the ice, so there's that. Might not be totally useless on a well coached team.
Insurance should be mandatory on all multiyear contracts.
It's likely prohibitively expensive to insure all contracts. The NHL has a league-wide insurance policy where each team pays premiums on their 5 biggest contracts and can spread that insurance across up to 7 players.*. That coverage requires the player to be out something like half a season or more before insurance kicks in. And the insurer can deny future coverage on a case by case basis based on past injuries. For example I doubt the Pens are insured against a future Crosby concussion.
Any insurance beyond that has to be done on a one-off or small team pool basis. Making the premiums a lot higher.
Given their respective contracts, Columbus could probably trade Clarkson with salary retained and still come out ahead on the bottom line if Horton is never playing again.
*The last detailed report we had of the NHL contract insurance system was many years ago, that's how it worked at the time. Could have been tweaked a bit since then, but I'd expect it's still close to that methodology.