I'd suspect the bond is there to ensure that Sky Blues fulfill their fixtures for the coming season, if SISU fall out with Blues or plead poverty due to not covering their costs at St Andrews then the bond gets kept by the EFL and Sky Blues will likely get thrown out of League 1. Blues will probably get a share of the bond for being accommodating.
Whole situation is a mess, despite the vitriol shown by some of their fans I do feel for them and wish that a way of keeping then in Coventry could have been found. However, the fact remains that if your tenant continues to try and wrestle your property away then why would you keep them in situ.
CCC had an asking price for the Ricoh. Wasps were prepared to pay it and therefore the stadium is ours. SISU had their chance to buy it a few years earlier but reneged.