Well, it is a bit of a non-story isn't it? Great digging by people on this site to find it out, but ultimately its SISU protecting any assets left in the company in case of liquidation.
This is pretty serious though. Unless SISU can secure half the ground/reduction in rent, then the club is going to die. The only other way it survives is if they can attract investment or a buyer. So far they haven't been able to do that.
They took out the debenture in March, when ACL/council and everyone else was saying the ricoh doesn't need the football club, so i don't blame SISU for thinking "oh shit, if they won't sell, and we can't find a credible buyer, then we'll have to wrap it up otherwise we'll keep losing money". Now in recent weeks, clearly the council have realised that the football club is important and critical to the city and the arena, and as such seem to be trying to ensure that he club survives. The only way they have said they'll agree to that is if SISU commit to re-investing revenue from the Ricoh into the club. Hence the assessment of business plans, etc. They want assurances before they agree.