In my opinion, if you are the head of any company and something this disastrous happens - it happened on your watch and whether directly involved or not you have to carry the can.
Thats what the big pay check is for- overall responsibility. Even if santy didn't leave you a bonus.
I have no doubt that Sr Cruz has absolutely nothing to do with the day to day running of the IT for BA. However it definitely is something that falls under his jurisdiction.
edit: What he has fallen down on is the recovery effort and dealing with passengers who need some pro active help, not just 'send in your receipts' . Most people in this forum know that reimbursement can take time and given the amount of claims to be processed I doubt if it will be quick.