Okay, I've watched more Twenty Twelve, along with both series of The Games again. Good news is that the show isn't plagiarised.
The biggest risk of failure that seems to be floated on Twenty Twelve is that the deliverance commission will look like idiots. With the exception of the two part boycott episode, none of the crises come close to threatening the Olympics. None of the storylines even criticise the Olympics that much!
Also, there's a lack of a real nemesis in Twenty Twelve. The Games has the (unseen) Olympics Minister as someone who'd frequently lie through his teeth, broker crap deals behind the backs of the organizers, offload unwanted responsibility onto them etc., in the full knowledge that SOCOG would either clean up the potentially Olympics-derailing mess, or take the fall for the screwup. Twenty Twelve has... baffling appearances from the real LOCOG head Seb Coe, who despite his title is only ever seen standing on the sidelines pleading "They're trying their best, really!".
The elephant in the room that Twenty Twelve seems to avoid eye contact with is the money involved. A large chunk of the plotlines in The Games are centered around various rorts and schemes to acquire more cash to pay for the Olympics, or the substantial amount of corruption/insider-dealing that occurs daily with multimillion dollar contracts. London is unquestionably a bigger cash sink than Sydney was, but no talk of money? None at all?
Anyway, the hallmark of good satire is if you can suspend your disbelief fully and think "that probably has happened somewhere". Twenty Twelve is a mildly entertaining sitcom, but as a satirical portrayal of the Olympics it is toothless. Much more interesting to just read about the real Olympics and some of the utterly insane shit the IOC has lumped onto the British public.
tl;dr - Go to TheEmpire or somewhere and watch The Games