That's a pretty good reason. I would trust somebody who has done it before.
The other teams in the division are better run now, and some are willing to spend like crazy, so the Nats can't afford to have the sort of poor drafts and shoddy development they had in the past and expect to compete. Even if the development situation was influenced by ownership, Rizzo hasn't drafted well. His staff has done well with international signings and he deserves credit for that, and he's made a number of very good trades, albeit to fill holes that should've been filled with internally developed talent. Overall, I can't see staying with him but I tend to agree with others that Leonsis would likely keep him.