I saw this earlier whilst purposely searching google results for doctor who from today just to see if anyone had come up with any good april fools jokes, and from the title it was obviously one, but skimming the article they made it even worse by including a fake quote from moffat. He would never admit his story lines had been found out if they had until the episode (s) in question had been aired.
I think the key to a good april fools joke is to post something subtle. had they said moffat was definitely leaving or clara was leaving early on and it would mostly be 12 and danny pink alone, these kind of things would be more beliveable, but going big on this day is a dead giveaway.
I think it would be hilarious if just once, Moffat gave out a real spoiler on april fools day. Obviously he wouldn't give anything major but maybe some small detail, but one which would sound a bit unbelieveable unless it came from a reliable source. It would be the greatest double bluff april fools ever, everyone would see it on the day, think 'yeah right' then when would realise how they had been had when it turned out to be true.