"I nonetheless personally don't think that open sourcing would necesarilly make ROL redundant." Surely not, since with their current track record they seem to try to achieve that goal by themselves
"After all, STD could have gone to Castle rather than ROL anyway. Presumably ROL brought expertise that STD valued?" AFAIK they asked CTL and ROL and then the decision was based on the reply/offering they got in return ... and perhaps to a certain amount that STD/Ad6 are closer to ROL than to CTL.