I don't remember it quite like that in this specific case. Rather I heard that there was push back against implementing a completion port model from somewhere (Redhat legal??) fearing patent action by MS. IBM had a mutual license agreement with MS I believe, which explains why AIX has something similar. The patents in question may even be in the set litigated over in the wake of Cutler moving to MS from DEC (which MS paid $$$ for and hence might be inclined to defend aggressively).