Renault were allowed to change for reliabilty issues.
The rumours circulating are that Ferrari are going to use that as an excuse. How FIA go about regulating how they are able to make such mods i dont know.
As a member of Ferraris haters club! i would have to admit it would be harsh to deny the request. They have already allowed virgin to alter the chasse. Its just how they go about regulating the change so it is just what they said they were going to change and nothing else.