Besides that not being realistic, I don't have a problem with it.
2 smaller examples:
1) Dontrelle Willis is owed $12 this year. Detroit put him on waivers and then worked out a deal to Arizona (including $). This is a much smaller scale than Z and less years on the deal.
2) Jose Contreras was signed to a 4 year, $32 million contract in December 2002. He was traded to the White Sox before 2 years of the contract were done because he struggled with the Yanks.
Again, not as much as Big Z (or even the clubhouse problems necessarily), but it happens. If a team thinks they can fix him, the Cubs can try to dump him (and they will pay a lot of his salary).
What is hurt by putting him on waivers?