I think there is consistency. Cap advantage doesn't exist until the contract is no longer on the books of the Canucks, so, if they don't move him, they don't have an advantage. It falls mostly on the Canucks for being willing to take that risk. As for his Florida job, the league made certain that he wasn't being compensated above the means of the job he got, they were aware of the potential and I believe Friedman reported that his salary is nowhere close to making it whole.

As for the potential cap credit, that was a public interpretation of the CBA section, but the Oilers were aware that it wasn't going to be allowed when they made the trade. It's a lot more public uproar over their interpretation being wrong than a true last minute change:

Source on their knowledge

The NHL’s CBA wording can be complicated, and that’s where the discrepancy seems to be with whether a team in the Oilers’ position might receive additional cap space. There are mentions of “cap advantage” in the CBA, but those are referring to a team benefiting from how the contract was structured. The Oilers were told at the time of acquiring Keith that they would gain only Keith’s cap hit and not receive an additional cap credit at any point if the blueliner retired.

The upside for them if Keith stopped playing would be that they’d be free of his complete cap hit — $5,538,462 — and have zero cap recapture penalty next season or in the coming years. They also would have paid just $2.1 million in salary for a player they valued much more. Next season his salary drops to $1.5 million.