Reason to make the deal: the Rockets wouldn't have to worry about Green's contract situation
As it stands now, the Rockets find themselves stuck on whether to extend Jalen Green or not. Green's contract expires after next season, although the Rockets could allow him to hit restricted free agency, since he's still on a rookie deal.
If they decide to go that route and he gets a greater deal than what they want to give him, they'd lose him for nothing. Trading him at least ensures they'd get something in return.
Green is eligible for a rookie extension after this season and he's already stated that he wants a max contract. Granted, he'd be foolish to say otherwise, as every player says this.
The Rockets likely don't want to give him an extension this summer, as it would be difficult to justify, based on his inconsistency this season (even if there are legitimate reasons for it). They wouldn't be dangling him as a trade piece (reportedly) if they planned on keeping him long term.
Trading Green would absolve the Rockets of giving him a contract extension, which they may not want to give him.