Sure, that's because CAS have the reputation for being impartial on this. But CAS is not strictly a legal entity, it is an arbitration service, and doesn't make the judgements on the basis of a particular statute law. Therefore the arguments being put to CAS would likely be entirely different to the arguments and the nature of any legal action through the actual courts.
On another matter, this from Simon Stone:
"About three weeks ago, Manchester City made a very detailed submission that extended to more than 100 pages.
"It has not gone unnoticed by the club that it is five years to the day since Uefa announced City had breached FFP rules and fined them £49m, although City received £33m back three years later after they met regulations.
"According to CFCB's own regulations, they cannot bring prosecutions more than five years after the event.
In the referral it is understood the CFCB said that through their submission there are further questions to be asked of City but, since their submission, none of these questions has been put to the club."
He's suggesting there that UEFA have rushed this to meet the five year deadline rather than following the due process. Interesting - and in itself would likely get it thrown out.