You could be right. War with Japan became almost inevitable when they occupied French Indo-China. It was simply a question of when. And it would be a way to goad Hitler.
On the other hand the US was really hoping to postpone the war for as long as it could, because we were not ready. Which means had Japan not moved when it did, this story would have hurt FDR for several months with people who leaned isolationist. Which could adversely effect defense bills.
Your last point is one of my main reasons I lean away from it being an intentional leak. If Japan had delayed attacking the United States until the spring, FDR would have been fighting the isolationists every step of the way. Judging from what we have seen with the rampant strikes, I’d be Lewis and his ilk would start causing problems as well. It would have been just too great a risk to take.
My personal feeling is it was leaked by someone who had sympathies towards the isolationists themselves. I bet you can’t guess who I’m thinking of though.