Maius Intra Qua Extra

Well, it would really depend on if you feel that it's wrong for a physician to treat and save the life of a heart attack victim who is unable to voice consent at the time. Or, if you prefer, is it wrong for a policeman to haul back to safety a person who's trying to commit suicide and yelling at him to let her jump? Because that's the correct real-world parallel.

It is not valid to compare Donna's situation to the current discussions about consent to sexual activity. There are certainly cases of the Doctor not respecting companions decisions that are questionable and can be compared to that, but Donna's is not one of them.