Therefore, I can't state this with any certainty, but I'll bet there is plenty about the early years of 'Doctor Who', when they were first finding their footing as to the dynamics of the world they were creating, which the Powers That Be would now love to take back.
Among these - and I'm NOT agreeing with these choices at all! - would be Susan as the Doctor's grand-daughter, the ability of the TARDIS to be miniaturized, and that time when the first Doctor turned to the camera and wished the TV audience a happy Christmas.
The footage for that segment is apparently lost, which might make some happy - they don't want the serious study of the show to be compromised, even if it is a kids' show.
But I could just be guessing on that.
Lots of TV characters are serlinguists, those who can talk directly to the audience in the Trueniverse - Rod Serling, of course, after whom the term was coined, Garry Shandling, George Burns, many TV commercial denizens, and even the crew from 'Hustle'. (They may not talk directly to the audience, but they do acknowledge its presence with winks and smirks aimed at the camera.)
I don't know if the Powers That Be are embarrassed by the Doctor's bit of serlinguism, but they can't deny it happened. As a matter of fact, they confirmed that the Doctor could do such a thing during the modern "recharge" of 'Doctor Who'. It happened during "The Shakespeare Code". Basically, here it is, all laid out in a triptych:
And here is the exact transcript for that snatch of dialogue:
Come on! We can have a good flirt later!
Is that a promise, Doctor?
Oh, fifty-seven academics just punched the air. Come on.
How would the Doctor know that fifty-seven academics were at that moment back in the modern day punching the air with their fists? To my mind, he knew that they were back in the Trueniverse, watching the adventure play out on their TV screens.
This knowledge that all the world's a soundstage is known as "tele-cognizance". David Addison of 'Moonlighting' was a tele-cognizant. ("I'm doing my part to clean up the airwaves. Just say no to innuendo!")
Another tele-cog would be Lt. 'Columbo'! (In "Last Salute To The Commodore", he requested absolute silence and wouldn't continue until even the soundtrack music was silenced. Upon which he said "Thank you.")
And of course, all serlinguists must be tele-cognizant.
Therefore, that was no fluke when the Doctor wished everyone those season's greetings.
He knows we're out there... watching.......
"Don't gang up on me! I don't write this stuff."