That’s what New York Magazine says, and Gawker shares the details.
Roberts is an anchor for Today Show competitor Good Morning America. Roberts was diagnosed with a rare blood disease, and multiple news outlets and famous folks showed their support as she battled against it. But NBC apparently told their personalities to refrain from making it public. From the NY Mag piece:
“Ann Curry was gone but not gone, which created a situation of spectacular awkwardness. Any trust that had existed between Curry and Today was shattered. When Robin Roberts left Good Morning America a month later to get treatment for MDS, Curry asked NBC if she could tweet a note of sympathy for the ABC co-host. NBC said no, afraid she was trying to aid the enemy.”
So the NBC Robin Roberts tweet never came to pass, and NBC looks like they have missed the point in spectacular fashion.