Probably because Stewart is probably keeping quiet and pocketing his wages? Apparantly Boehly's original choice for the job, Boehly didn't want to admit the mistake and sack him when Winstanley was brought in, so set up the joint position. Would be interesting to get the inside low-down on how...
I suspect the reason might be that Boehly didn't want to admit he'd dropped a bollock, so wouldn't sack the man he originally chose (the one who negotiated the £62M Cucurella deal).