I think reading between the lines (and I have no real insight but being in Canberra am a bit closer to the action) that the problem is a bit of all that we've read.
As Nathan observed, the club is really two clubs in one and the DT side is the one pushing the VMX titles. Now, the Kumagutza track DID need a lot of work but Fred and his team have certainly done the majority of that.
However, there have been concerns expressed and I understand that was raised with MA who (rightly) have looked into the situation. I cannot comment on how that went, but clearly they have raised the bar a little in terms of how much more work was needed, more than the club had anticipated.
I would guess that the cost of that work, given the result will not be a hugely profitable event, is more than the club can bear.
So, it's a little of everything. I always felt that the club had taken on an ambitious job but as Firko notes they were having a good shot at it. Sadly, it hasn't panned out.
So, rather than bag the ACTMCC or MA, the best thing is to move on and see if another club can step up. There's still time.