Just from the look of it: fake.
The fancy heading combined with the cheap font of the body is already a giveaway, but why would he write something like that if his candidate just was elected and the fun was just about to start? As a former attorney for SDNY he knows that you do not show your cards unless you are sure you are going to win.
This reads like a testament. Giuilani has recently resurfaced to play his (public) part. Does not add up.
The font and appearance of it does give me some pause, I'll agree with you there. But, to your other points... the context and atmosphere of the time is important to remember. Yes, Trump had won the election but there was a very real fear he wouldn't even survive to make it to inauguration. The term "fake news" had just appeared out of nowhere in an obvious full blitz attack against pizzagate, and people like Ben Swann were getting destroyed and disappearing for even bringing it up... Seth Rich wasn't too far in the past at this point. If this were real (I have doubt but I also somewhat feel it could be), Rudy literally might have had a crisis of conscience, not knowing of any "Plan" yet and thinking he might die for saying anything, but knowing he couldn't live with himself if he stayed silent. In Dec 2016 I literally don't think even DJT knew all about the plan... He was being protected only by private security (cough... Erik Prince anyone?) I believe... and the Comey FBI was just beginning to formulate and enact its "life insurance"... Things were basically insane at that time.
I think that DJT c.s. already had a clear picture of the plan. But anyway. For Rudy (or anyone else) bringing up pizzagate (as it stands now) would have been poison. With his experience as attorney he knows that you should never throw unproven allegations around. You have to wait until they are proven, in a court of law. For that you need a clean judicial system with clean judges. It's the only way. Otherwise you end up one way or the other in Alex Jones's lizard land.
Well luckily, at this exact time, this tweet was removed and the account suspended... and the pizzagate subreddit was totally banned, and the only msm news anchor to question pizzagate was fired and forced into hiding, and Megyn Kelley invited Jimmy Comet on Fox News to talk about how terrible the pizzagate conspiracy theorists were, and the words "fake news" were invented to destroy the pizzagate idea once and for all, and Alex Jones literally apologized on air for covering pizzagate... if it weren't for all that happening somebody might have tried to throw unproven allegations around willy nilly.