I think Cassel are being over-zealous in their guarding of the English language. As I see it, "prompting" refers to the whole situation expressed in the preceding clause, not the subject of the clause. We say "His murder has prompted..." But in starting a completely new sentence, I would see 'prompting' as then referring to the whole meaning of the preceding sentence, or as a reaction to one or other of the participants being involved. Only what comes after "this has prompted..." will clarify which.
"This has prompted Amnesty International to condemn the actions of the Palestinian Security Forces..."
Student or Learner