No this doesn't make much sense. The NBA can't set a precedent that they dictate what is considered "appropriate" value in a trade. Legally, the Heat can trade LeBron James for Brook Lopez if it meets salary regulations.
The Hornets thing didn't count, because the NBA was acting owner. The NBA can't say "DeAndre is too much for KG" or "KG is too much for DeAndre". That's nonsense. And even if they did, they can't dictate what constitutes appropriate value to make it match. They can't say "boston needs to give up a draft pick for this to be even". WHy a draft pick? Why not Jason Terry? What one team might consider an overpaid albatross of a contract... another might consider a valuable high-level bench player with championship experience and a history of winning. The is no way the rationalization is literally "DeAndre is too much for KG", otherwise every single trade would be under scrutiny. Revolk the James Harden trade... the Rockets didn't give up enough. Send Pau back to Memphis... LA didn't give up enough. Etc.
Do they have the authority to dictate what is appropriate compensation for releasing a coach from his contract? Has anyone ever done that? Is that even legal?
They have the authority, technically, if they feel the only reason the Clippers are giving up what they are giving up is because they know Doc Rivers will be released and sign with them, and KG will agree to waive his no trade only because Doc will be the coach there.
In other words, the league office has "jurisdiction" here because there's reason to believe the deals are not functionally separate -- one has to happen in order for the other to happen, and so the compensation the Clippers are giving up in one thing is related to what the Celtics are giving up in the other things.
Technically, that's against the rules.
Still, it's silly that the league is blocking this. The teams have negotiated hard and come up with an exchange that each side thinks is more or less fair.
It seems like other teams in the league are complaining b/c one of their rivals is about to get a lot better and they don't want it to happen.