The acquisition price (so what it did cost to buy the company) was $2.4B.
The other $1.2B were for retention bonuses, meaning money paid to key staff of the company that is paid to each one of them
only if they remain in the company for a certain amount of years and depending on the case (depending on the acquisition sometimes is signed and sometimes doesn't, or sometimes it only applies to execs) if the acquired company achieves certain numbers on its first years.
While I lean towards your position more than the other side, I still think your position is unnecessary.
You don't judge a 2.4 billion dollar purchase before they release a single new game. That's what crazy people do.
You start judging a 2.4 billion dollar purchase about 10 years after the fact because that's when you really see what the fruits of the purchase look like.
The people who desperately want to judge them can't be taken seriously.
Big acquisitions are made looking at a long term plan, specially in a business like the current AAA gamedev scenario where games take around or over half a decade to be made.
Obviously performance keeps tracked periodically and constantly, but when acquisitions are made they take for granted that the first years are just for integrating the team to the workflow and many different things of the acquirer, many changes and adjustments are made and there's a learling process for both sides, plus are also a period where pre-acquisition projects are still being done and released and sometimes they aren't given the same attention or support than later projects already started since the start within the acquirer.
Meaning, acquired companies are normally given by the acquirer a certain free pass or special treatment during some years if there isn't any big red flag. It's normally in the mid term (around 3-5 years after acquisition) when they start to get serious about achieving very ambitious goals to justify the acquisition and recoup the investment, which normally isn't achieved before the first 5-10 years (some of them are never recouped and it's fine for them).
So yes, unless there's some 'apocalypse', they won't take conclusions until almost 10 years or so. They will want to see how the end tail of Destiny 2 worked, how Marathon, 'gummy bears' and Destiny mobile game performed, plus pretty likely some movie/tv adaptations they may have in the work and a game or two more that they may have released by then, plus also the support they given to the non-Bungie SIE GaaS titles.
I'm pretty sure that with all this combined they'll have recouped the acquisition in less than 10 years and will be happy with them.